feat: allow `.` in proxy path escape pattern

[testinfected]

Add the . character to the proxy path escape pattern so that we can use e.g. domain names as cluster names without breaking the query parameters escaping.

See https://github.com/oam-dev/cluster-gateway/issues/150

[FogDong]

@wonderflow Can you help to merge this?

[wonderflow]

Thanks for contributing, I can't merge until we fixed the test and signed the DCO.

[FogDong]

Please sign the DCO so that we can merge the PR with git commit -s, thanks!