fix: generate native image configurations for Gapics

[mpeddada1]

Notable Changes:

• This PR leverages the Writer class to parse necessary information such as package name and class name from the collection of GapicClass objects that are returned by the Composer. It then uses that information to generated a reflect-config.json file.
• The drawback of this change is that it only includes a subset of classes, particularly, the ones generated by the gapic generator. We need to also include the classes that are generated by the standard java_proto_library bazel rule.

[sonarqubecloud]

[gapic-generator-java-root] SonarCloud Quality Gate failed.   

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0.0% Coverage
0.0% Duplication

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[sonarqubecloud]

[java_showcase_integration_tests] Kudos, SonarCloud Quality Gate passed!   

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No Coverage information
No Duplication information

[sonarqubecloud]

[java_showcase_unit_tests] Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[burkedavison]

Like the other PR, (if we want to continue considering this option) let's please update this PR to:

• Apply to showcase
• Invoke the showcase native image tests
• Remove the RunReachabilityHandlersConcurrently argument
• Remove the Feature classes using reachability handlers

[mpeddada1]

Closing in favor of #1841