feat: Adding extension server policy handling.

[liorokman]

What this PR does / why we need it: This PR implements extension server policies which can be attached to HTTP listeners.

See the full description in the issue (#2975)

Which issue(s) this PR fixes: Fixes #2975

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 55.55556% with 124 lines in your changes are missing coverage. Please review.

Project coverage is 67.26%. Comparing base (76c08e6) to head (3772293). Report is 6 commits behind head on main.

Files	Patch %	Lines
internal/provider/kubernetes/status.go	3.84%	24 Missing and 1 partial :warning:
internal/gatewayapi/runner/runner.go	21.42%	20 Missing and 2 partials :warning:
internal/gatewayapi/resource.go	0.00%	18 Missing :warning:
internal/provider/kubernetes/controller.go	64.58%	14 Missing and 3 partials :warning:
internal/extension/registry/xds_hook.go	0.00%	16 Missing :warning:
internal/gatewayapi/extensionserverpolicy.go	84.90%	10 Missing and 6 partials :warning:
internal/provider/kubernetes/status_updater.go	25.00%	8 Missing and 1 partial :warning:
internal/message/types.go	0.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3371      +/-   ##
==========================================
- Coverage   67.77%   67.26%   -0.52%     
==========================================
  Files         166      167       +1     
  Lines       20037    20282     +245     
==========================================
+ Hits        13581    13643      +62     
- Misses       5466     5645     +179     
- Partials      990      994       +4     

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[guydc]

cc @AliceProxy

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

@AliceProxy @arkodg @guydc PTAL

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest

[liorokman]

/retest