Greenfield: Implement direct controller, E2E fixtures, and fuzzer for VideoStitcherCDNKey (#11185)

# Description

This Pull Request implements the direct controller, E2E test fixtures,
and schema round-trip fuzzer for the Greenfield resource
`VideoStitcherCDNKey`.

## Implementation Details

1. **Direct Controller**:
- Implemented
`pkg/controller/direct/videostitcher/videostitchercdnkey_controller.go`
to handle resource lifecycle operations: `Find`, `Create`, `Update`,
`Delete`, and `Export` via the official Google Cloud Go Video Stitcher
REST/gRPC client library.
- Leveraged top-level field diffing using the `tags` package for robust
in-place updates.
- Automatically registered the direct controller model and mapped
resources.

2. **Mapper & Code Generation**:
- Modified `generate.sh` in the API group directory to enable automatic
mapping.
- Generated conversion code (`mapper.generated.go`) to convert between
the KRM spec and the GCP proto representation.

3. **Schema Round-Trip Fuzzer**:
- Implemented `videostitchercdnkey_fuzzer.go` to register the KRM schema
fuzzer.
- Hand-wrote `videostitchercdnkey_fuzzer_test.go` and verified the
translation layer for zero-data-loss and full compatibility.

4. **E2E Test Fixtures**:
- Scaffolds both `minimal` and `maximal` test cases under
`pkg/test/resourcefixture/testdata/basic/videostitcher/` to verify CRUD
lifecycle.

---

Fixes #11178

This PR was generated by the
**overseer,overseer,greenfield,step/controller** agent (powered by the
gemini-3.5-flash model).

Author: acpana

apis/videostitcher/v1alpha1/generate.sh

@@ -28,7 +28,11 @@ go run . generate-types \
   --api-version videostitcher.cnrm.cloud.google.com/v1alpha1 \
   --resource VideoStitcherCDNKey:CdnKey
 
-# Note: We do not run generate-mapper here as this PR is for types/CRD/Identity only.
+go run . generate-mapper \
+  --service google.cloud.video.stitcher.v1 \
+  --api-version videostitcher.cnrm.cloud.google.com/v1alpha1
 
 cd ${REPO_ROOT}
 dev/tasks/generate-crds
+
+go run -mod=readonly golang.org/x/tools/cmd/goimports@${GOLANG_X_TOOLS_VERSION} -w pkg/controller/direct/videostitcher/

go.mod

@@ -85,6 +85,7 @@ require (
 	cloud.google.com/go/spanner v1.91.0
 	cloud.google.com/go/speech v1.35.0
 	cloud.google.com/go/storage v1.62.0
+	cloud.google.com/go/video v1.32.0
 	cloud.google.com/go/vmwareengine v1.8.0
 	cloud.google.com/go/workflows v1.19.0
 	cloud.google.com/go/workstations v1.1.6

go.sum

@@ -118,6 +118,7 @@ import (
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/vertexai"
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/vertexai/examplestore"
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/vertexai/featuregroup"
+	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/videostitcher"
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/vmwareengine"
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/workflowexecutions"
 	_ "github.com/GoogleCloudPlatform/k8s-config-connector/pkg/controller/direct/workflows"