Fix/8976 modernize grpc gradle

[tejas5038]

Description

Fixes #

Checklist

Testing

• I have tested this change on a live environment and verified it works as intended.
• Tests pass: mvn clean verify required
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only

Compliance & Style

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample

Post-Approval Actions

• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request modernizes the Gradle build configuration across the api, client, and server subprojects by replacing the deprecated compile configuration with implementation, updating the application plugin configuration to use the application block, and updating the jar task to use runtimeClasspath. However, changing the gRPC dependencies in the api project to implementation will break compilation for the client and server projects, which transitively rely on those dependencies. It is recommended to use the api configuration instead, which also requires applying the java-library plugin.

[gemini-code-assist]

Changing these dependencies to implementation will break the compilation of the client and server subprojects. Since client and server depend on project(':api') and directly reference gRPC classes (such as ManagedChannel, Server, StreamObserver, etc.), these dependencies must be exposed transitively on their compile classpaths.

To fix this, use the api configuration instead of implementation. Note that you will also need to change apply plugin: 'java' to apply plugin: 'java-library' at the top of this file (line 17) to make the api configuration available.

  api "io.grpc:grpc-netty:${grpcVersion}"
  api "io.grpc:grpc-protobuf:${grpcVersion}"
  api "io.grpc:grpc-stub:${grpcVersion}"