Replace GOCC parser-generator with PGPG (#2015)

* Porting

* Update some tests that depend on AST-print output

* iterating on GOCC -> PGPG

* iterating

* iterating

* iterating

* iterating

* iterating

* Modify expout files that need only AST-print-syntax updates

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* iterating

* sync test cases from mlr-6.17.0, except AST-prints ...

* sync test cases from mlr-6.17.0, except AST-prints ...

* Fix lashed emit for $* and @*

* Fix --1 and ++1 chained unary ops

* Emit with function callsite

* test cases

* dot operator

* M_PI and M_E

* Iterating on lashed emit cases

* error-wording differences

* rm some should-fail files

* Fix issue with leading semicolon

* trailing comma in func params; most AST-print deltas

* error-wording delta

* fix unset all

* AST-print deltas

* go mod tidy: forced `go 1.25` to `go 1.25.0`

* Depend on PGPG v1.0.0

* Fix Windows CI failure

* Remove cmd/experiments/dsl_parser

* GOCC -> PGPG

* neaten

* Fix regex issue found in doc gen

docs/src/manpage.md

@@ -3820,5 +3820,5 @@ This is simply a copy of what you should see on running `man mlr` at a command p
        MIME Type for Comma-Separated Values (CSV) Files, the Miller docsite
        https://miller.readthedocs.io
 
-                                  2026-03-06                         4mMILLER24m(1)
+                                  2026-03-16                         4mMILLER24m(1)
 </pre>

docs/src/manpage.txt

@@ -3799,4 +3799,4 @@
        MIME Type for Comma-Separated Values (CSV) Files, the Miller docsite
        https://miller.readthedocs.io
 
-                                  2026-03-06                         4mMILLER24m(1)
+                                  2026-03-16                         4mMILLER24m(1)

docs/src/reference-dsl-differences.md

@@ -64,12 +64,7 @@ error.
 </pre>
 <pre class="pre-non-highlight-in-pair">
 mlr: cannot parse DSL expression.
-mlr: Parse error on token "$y" at line 6 column 3.
-Please check for missing semicolon.
-Expected one of:
-  ␚ ; > >> | ? || ^^ && =~ !=~ == != <=> >= < <= ^ & << >>> + - .+ .- *
-  / // % .* ./ .// . ?? ??? ** [
-
+mlr: parse error: unexpected field_name ("$y")
 </pre>
 
 ## elif

docs/src/reference-dsl-higher-order-functions.md

@@ -776,12 +776,7 @@ As of September 2021, immediately invoked function expressions (IIFEs) are not p
 </pre>
 <pre class="pre-non-highlight-in-pair">
 mlr: cannot parse DSL expression.
-mlr: Parse error on token "(" at line 4 column 35.
-Please check for missing semicolon.
-Expected one of:
-  ; } > >> | ? || ^^ && =~ !=~ == != <=> >= < <= ^ & << >>> + - .+ .- * /
-  // % .* ./ .// . ?? ??? **
-
+mlr: parse error: unexpected lparen ("(")
 </pre>
 
 but this does:

docs/src/reference-dsl-output-statements.md

@@ -457,7 +457,7 @@ to files.
 Keep in mind that out-of-stream variables are a nested, multi-level [map](reference-main-maps.md) (directly viewable as JSON using `dump`), while Miller record values are as well during processing -- but records may be flattened down for output to tabular formats. See the page [Flatten/unflatten: JSON vs. tabular formats](flatten-unflatten.md) for more information.
 
 * You can use `emit1` to emit any map-valued expression, including `$*`, map-valued out-of-stream variables, the entire out-of-stream-variable collection `@*`, map-valued local variables, map literals, or map-valued function return values.
-* For `emit`, `emitp`, and `emitf`, you can emit map-valued local variables, map-valued field attributes (with `$`), map-va out-of-stream variables (with `@`), `$*`, `@*`, or map literals (with outermost `{...}`) -- but not arbitrary expressions which evaluate to map (such as function return values).
+* For `emit`, `emitp`, and `emitf`, you can emit map-valued local variables, map-valued field attributes (with `$`), map-valued out-of-stream variables (with `@`), `$*`, `@*`, map literals (with outermost `{...}`), or map-valued function return values (e.g. `emit f($a, $b)`).
 
 The reason for this is partly historical and partly technical. As we'll see below, you can do lots of syntactical things with `emit`, `emitp`, and `emitf`, including printing them side-by-side, indexing them, redirecting the output to files, etc. What this means syntactically is that Miller's parser needs to handle all sorts of commas, parentheses, and so on:
 

docs/src/reference-dsl-output-statements.md.in

@@ -209,7 +209,7 @@ to files.
 Keep in mind that out-of-stream variables are a nested, multi-level [map](reference-main-maps.md) (directly viewable as JSON using `dump`), while Miller record values are as well during processing -- but records may be flattened down for output to tabular formats. See the page [Flatten/unflatten: JSON vs. tabular formats](flatten-unflatten.md) for more information.
 
 * You can use `emit1` to emit any map-valued expression, including `$*`, map-valued out-of-stream variables, the entire out-of-stream-variable collection `@*`, map-valued local variables, map literals, or map-valued function return values.
-* For `emit`, `emitp`, and `emitf`, you can emit map-valued local variables, map-valued field attributes (with `$`), map-va out-of-stream variables (with `@`), `$*`, `@*`, or map literals (with outermost `{...}`) -- but not arbitrary expressions which evaluate to map (such as function return values).
+* For `emit`, `emitp`, and `emitf`, you can emit map-valued local variables, map-valued field attributes (with `$`), map-valued out-of-stream variables (with `@`), `$*`, `@*`, map literals (with outermost `{...}`), or map-valued function return values (e.g. `emit f($a, $b)`).
 
 The reason for this is partly historical and partly technical. As we'll see below, you can do lots of syntactical things with `emit`, `emitp`, and `emitf`, including printing them side-by-side, indexing them, redirecting the output to files, etc. What this means syntactically is that Miller's parser needs to handle all sorts of commas, parentheses, and so on:
 

docs/src/reference-main-regular-expressions.md

@@ -383,7 +383,8 @@ ASCII character classes:
     [[:word:]]     word characters (== [0-9A-Za-z_])
     [[:xdigit:]]   hex digit (== [0-9A-Fa-f])
 
-Unicode character classes are those in unicode.Categories and unicode.Scripts.
+Unicode character classes are those in unicode.Categories,
+unicode.CategoryAliases, and unicode.Scripts.
 
 func IsWordChar(r rune) bool
 type EmptyOp uint8