fix(projects): resolve IntegrationHarbor projectIdRef

[henrysachs]

Description of your changes

Fixes #446

Why

Project IntegrationHarbor has projectIdRef and projectIdSelector, but no ResolveReferences. A resource that set only the ref kept an empty projectId.

What changed

• Add IntegrationHarbor.ResolveReferences in apis/namespaced/projects/v1alpha1/referencers.go. It matches the other project kinds, such as IntegrationMattermost.
• Regenerate the cluster-scoped copy (apis/cluster/projects/v1alpha1/zz_referencers.go).
• Add a ResolveReferences unit test with a mock reader, plus its generated cluster copy.

Scope

Only IntegrationHarbor was missing a resolver. Every other kind with *Ref fields under apis/{namespaced,cluster}/{groups,projects,instance} has one. Some are hand-written in referencers.go. Others are generated in zz_generated.resolvers.go from +crossplane:generate:reference markers: AccessToken, DeployKey, PipelineSchedule, ProjectShareGroup, ProtectedBranch, ProtectedEnvironment.

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Verification

• go build ./..., go test ./apis/... ./pkg/{namespaced,cluster}/controller/projects/integrationharbor/..., and golangci-lint on apis/{namespaced,cluster}/projects all pass. go generate -tags generate ./apis/... leaves no diff.
• The new test fails to compile without the fix because ResolveReferences is undefined. With the fix it passes.
• Live test on kind with GitLab 19.4. I applied a Group, a Project, and an IntegrationHarbor that set only projectIdRef. projectId resolved to the project ID (654778), and the resource became Ready and Synced. GET /projects/654778/integrations/harbor returned active: true with the configured url, project_name, and username. After delete, the integration showed active: false and empty properties.