test: allow installation using a specified GatewayAPI commit

[tao12345666333]

What this PR does / why we need it:

There are two ways to install GWAPI CRDs in our testing:

• install from go mod

  kubernetes-ingress-controller/test/envtest/setup.go

  Line 130 in 2888908

  gatewayCRDPath := filepath.Join(build.Default.GOPATH, "pkg", "mod", "sigs.k8s.io", "gateway-api@"+consts.GatewayAPIVersion, "config", "crd", "experimental")

• install from GitHub via kustomize

  kubernetes-ingress-controller/test/e2e/features_test.go

  Line 280 in 2888908

  require.NoError(t, clusters.KustomizeDeployForCluster(ctx, env.Cluster(), consts.GatewayStandardCRDsKustomizeURL))

However, kustomize does not support the use of short commits generated by go mod,
and go mod also does not support the use of full commit hashes.

This PR introduces a new variable, GATEWAY_API_PACKAGE_VERSION. It will automatically resolve the package version in dependencies through go mod and allow us to use the full commit hash to use the GATEWAY API package.

Which issue this PR fixes:

Special notes for your reviewer:

This PR is from
91d2c60

I used a specific commit hash of GWAPI in #5776 and it has passed the test.

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 74.0%. Comparing base (2888908) to head (2d26a59).
Report is 36 commits behind head on main.

❗ Current head 2d26a59 differs from pull request most recent head c568899. Consider uploading reports for the commit c568899 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #5808     +/-   ##
=======================================
+ Coverage   73.9%   74.0%   +0.1%     
=======================================
  Files        176     176             
  Lines      18185   18185             
=======================================
+ Hits       13445   13468     +23     
+ Misses      3737    3721     -16     
+ Partials    1003     996      -7     

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[rainest]

I maybe misread somewhat earlier; looking again that value maybe isn't used outside that one Makefile generate target, i.e. not in tests per se?

envtest doesn't fail when invoked direct from go test, so I guess that's double confirmation this doesn't introduce any new environment requirement.

[tao12345666333]

Yes.