Restructure dagger-grpc-server-processor sources. #5286

Job	Run time
Validate Dagger version	21s
Gradle build	15s
Bazel tests	2m 30s
Bazel build	4m 16s
Artifact Java local tests	3m 24s
Artifact Android local tests (AGP 8.1.1)	9m 15s
Test Hilt Gradle plugin	10m 0s
Artifact verification tests	11m 17s
Artifact Android emulator tests (API ${{ matrix.api-level }})	0s
Build Hilt Gradle plugin against latest AGP version	0s
Clean up GitHub Action caches	9s
Publish snapshot	0s
	41m 27s

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