feat: Support blackhole, prohibit and unreachable route types

It is useful and common practice to configure the routes with blackhole,
prohibit, and unreachable route types when users have BGP routing
setups.

Notice that this feature is only for nm provider using
`network_connections` variable. Configuring blackhole, prohibit, and
unreachable route types is also supported by using `network_state` since
nmstate version 2.2.20 (the setting name is `route-type`).

Resolves: https://issues.redhat.com/browse/RHEL-19579

Signed-off-by: Wen Liang <liangwen12year@gmail.com>

examples/route_type_support.yml

@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: BSD-3-Clause
+---
+- name: Manage route type routes
+  hosts: all
+  tasks:
+    - name: Configure connection profile and route type routes
+      import_role:
+        name: linux-system-roles.network
+      vars:
+        network_connections:
+          - name: eth0
+            interface_name: eth0
+            state: up
+            type: ethernet
+            autoconnect: true
+            ip:
+              dhcp4: false
+              address:
+                - 198.51.100.3/26
+                - 2001:db8::2/32
+              route:
+                - network: 198.51.100.64
+                  prefix: 26
+                  gateway: 198.51.100.6
+                  metric: 4
+                  table: 30200
+                - network: 198.53.100.18
+                  prefix: 32
+                  metric: 20
+                  type: blackhole
+                  table: 30200
+                - network: 198.53.100.12
+                  prefix: 32
+                  metric: 24
+                  type: unreachable
+                  table: 30200
+                - network: 198.53.100.10
+                  prefix: 32
+                  metric: 30
+                  type: prohibit
+                  table: 30200
+                - network: 2001:db8::4
+                  prefix: 128
+                  metric: 2
+                  type: blackhole
+                  table: 30600
+                - network: 2001:db8::6
+                  prefix: 128
+                  metric: 4
+                  type: prohibit
+                  table: 30600