mesh: switch proxy configuration controller to use bound refs and the cache

[rboyer]

Description

This switches the proxy configuration controller from using the custom bimapper caching to using the common controller caching system.

follows https://github.com/hashicorp/consul/pull/20598

This also adds bound references to the ComputedProxyConfiguration type.

Testing & Reproduction steps

• The existing tests were retained.

PR Checklist

• [x] updated test coverage
• [ ] ~external facing docs updated~
• [ ] appropriate backport labels added
• [ ] ~not a security concern~