connection policy: add local_ip matcher

[mohammed90]

This is for discussion, because I haven't thoroughly vetted the idea but curious if we can introduce more matchers to behave more like the HTTP handlers matchers.

It might resolve cases like #5771, depending on the use case.

[mohammed90]

Changing the PR to draft until I add tests and we have consensus on the discussion whether this is a good change

[mholt]

I like where this is going.

What if we just start with the local IP matcher and then see about adding the complexity of the matcher sets later if we feel it is needed based on real-world feedback?

[mohammed90]

What if we just start with the local IP matcher and then see about adding the complexity of the matcher sets later if we feel it is needed based on real-world feedback?

Done.

[mholt]

Cool, thank you!

I wonder if we should use this in the Caddyfile parser when crafting TLS connection policies -- instead of always using ServerName, which will be empty then the host is the IP address.

Not for this PR, but just thinking for future improvement.