docs: add information about spotless for code formatting

[jamesarich]

Adds spotless doco to CONTRIBUTORS.md

Clarify that spotless is used for automated code formatting and provide commands for applying formatting and installing a pre-push Git hook.

[jsoberg]

I feel targeted 😅

[jamesarich]

I feel targeted 😅

I've been meaning to, you're a good reminder ;)

[jsoberg]

Huh I'm actually getting a failure from within Spotless' install task:

1 problem was found storing the configuration cache.
- Task `:app:spotlessInstallGitPrePushHook` of type `com.diffplug.gradle.spotless.SpotlessInstallPrePushHookTask`: invocation of 'Task.project' at execution time is unsupported with the configuration cache.
  See https://docs.gradle.org/9.0.0/userguide/configuration_cache_requirements.html#config_cache:requirements:use_project_during_execution
  
  ...
  
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:spotlessInstallGitPrePushHook'.
> Invocation of 'Task.project' by task ':app:spotlessInstallGitPrePushHook' at execution time is unsupported with the configuration cache.

[jamesarich]

Huh I'm actually getting a failure from within Spotless' install task:

1 problem was found storing the configuration cache.
- Task `:app:spotlessInstallGitPrePushHook` of type `com.diffplug.gradle.spotless.SpotlessInstallPrePushHookTask`: invocation of 'Task.project' at execution time is unsupported with the configuration cache.
  See https://docs.gradle.org/9.0.0/userguide/configuration_cache_requirements.html#config_cache:requirements:use_project_during_execution
  
  ...
  
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:spotlessInstallGitPrePushHook'.
> Invocation of 'Task.project' by task ':app:spotlessInstallGitPrePushHook' at execution time is unsupported with the configuration cache.

mm i do remember having to run it with --no-configuration-cache i'll add that

[jsoberg]

Ah I can probably fix that on Spotless' end, they just need to grab the root dir before executing the task

[jsoberg]

Re: spotless - diffplug/spotless#2586

Once that gets merged in and we update spotless I'll update our docs so that we don't need the config cache disable flag. I tested with maven-local install and it worked fine 👍