[sdk-platform-java] Enable iterative troubleshooting of local generator changes with protos in the googleapis/ repo

In order to verify client generation changes with protos in googleapis and the local generator modifications, we need to do the following:
1. Make the [specified modifications in googleapis/](https://github.com/googleapis/sdk-platform-java/blob/main/gapic-generator-java/DEVELOPMENT.md#running-the-plugin-under-googleapis-with-local-gapic-generator-java).
2. Call `bazel build ...` in googleapis/ to generate the tar.gz file for the client library in the bazel-bin directory.
3. Manually unzip the tar.gz files in the desired location and point your IDE there.

Unzipping the tar.gz every time there is a modification to the code being generated can be a little cumbersome and requires some manual effort especially if the generator changes are iteratively being testing. There may be an opportunity for this to be automated.