[FR] Eliminate version control noise when changing platforms due to google-services-desktop being modified

### Feature proposal

* Firebase Component: Core

When changing platforms the google-services-desktop.json file in the streaming assets folder is modified to reflect the change in target platform.

This results in the file ping ponging around from being changed user to user with everyone having a different local configuration.

If this is for editor only emulation (suggested here https://github.com/firebase/quickstart-unity/issues/1092) then it should be stored somewhere else, perhaps the Temp folder.

If this is required for runtime, then it should be auto-generated at build time and cleaned up after the build is finished (similar to what Unity Cloud Services does - if you peek at the StreamingAssets folder during a build you can see that they inject some files there that they then clean up after the build is complete)