chore(deps): bump gateway-api from 1.1.0 to 1.2.0 and adjust code

[programmer04]

What this PR does / why we need it:

Bumps version of gateway-api from 1.1.0 to 1.2.0 and makes required adjustments to make code compile and test pass (bump KTF to v0.1.7).

Furthermore, change the sorting of headerMatches by names from slice.Sort to slice.StableSort to fulfill the code commenter's desire always to have the same order. Bumping the Go version to 1.23 is required to make linitng pass.

Which issue this PR fixes:

Replaces #6543

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.3%. Comparing base (35b1374) to head (3bea8d8).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #6571     +/-   ##
=======================================
+ Coverage   69.5%   72.3%   +2.7%     
=======================================
  Files        202     202             
  Lines      25796   25856     +60     
=======================================
+ Hits       17935   18694    +759     
+ Misses      6853    6150    -703     
- Partials    1008    1012      +4     

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