Add GrpcHealthCheckedEndpointGroupBuilder

[wvuong]

Motivation:

Add GrpcHealthCheckedEndpointGroupBuilder which builds a health checked endpoint group whose health comes from a standard gRPC health check service result.

Modifications:

• Adds GrpcHealthCheckedEndpointGroupBuilder which extends AbstractHealthCheckedEndpointGroupBuilder and creates a new health check function
• Adds GrpcHealthChecker which is the health check function that creates and uses a gRPC HealthGrpc stub to check the gRPC health service on the endpoint. If the health check response is SERVING, it is healthy. It is unhealthy if the response is not SERVING or if there was a request failure.
• Adds tests.

Result:

• A user can create a health checked endpoint group that is backed by a gRPC health check service.
• Closes Support for gRPC health check endpoint #5930

[CLAassistant]

All committers have signed the CLA.

[github-actions]

🔍 Build Scan® (commit: 05f93c7)

Job name	Status	Build Scan®
build-ubicloud-standard-16-jdk-8	✅	https://ge.armeria.dev/s/royvjj7sslib6
build-ubicloud-standard-16-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/3wtorc7ldc3li
build-ubicloud-standard-16-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/uwhxkjr726fg4
build-ubicloud-standard-16-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/fm2ffg7w5ed44
build-ubicloud-standard-16-jdk-17-leak	✅	https://ge.armeria.dev/s/vpi6onaxw7lfi
build-ubicloud-standard-16-jdk-11	✅	https://ge.armeria.dev/s/z5fwz5nm42mjm
build-macos-latest-jdk-21	✅	https://ge.armeria.dev/s/j5sirz6td74vi