Configuration Blueprints: add new example for firewall+vrf. (backport #1482)

[mergify]

Change Summary

Configuration Blueprints: add new example for firewall+vrf. Also add note about usage of inbound and outbound interface when interface is attached to a non-default vrf.

Related Task(s)

Related PR(s)

Backport

Valid also for Sagitta

Checklist:

• I have read the CONTRIBUTING document

  ---

  This is an automatic backport of pull request Configuration Blueprints: add new example for firewall+vrf. #1482 done by Mergify.

[mergify]

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Changes to be committed:
	new file:   docs/_static/images/firewall-and-vrf-blueprints.png
	new file:   docs/configexamples/firewall.rst
	new file:   docs/configexamples/fwall-and-vrf.rst
	modified:   docs/configexamples/index.rst
	modified:   docs/configuration/firewall/ipv4.rst
	modified:   docs/configuration/firewall/ipv6.rst

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   docs/configexamples/zone-policy.rst

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally