GitHub Actions cache fixes

[3flex]

Summary of changes:

• Runs Gradle tasks with gradle-build-action@v2. This handles running Gradle tasks and caching various outputs. v2 is in beta, but once it's stable it will be supported by Gradle and recommended as the canonical way to run Gradle tasks on GitHub Actions.
• Enable Gradle's configuration cache for jobs that support it, which will reduce the job's execution time

Blocked until gradle-build-action v2 goes into production release as the configuration syntax could potentially change.

[codecov]

Codecov Report

Merging #3723 (8a66d34) into main (7479bda) will decrease coverage by 0.16%.
The diff coverage is n/a.

❗ Current head 8a66d34 differs from pull request most recent head d489a49. Consider uploading reports for the commit d489a49 to get more accurate results

@@             Coverage Diff              @@
##               main    #3723      +/-   ##
============================================
- Coverage     84.27%   84.10%   -0.17%     
+ Complexity     3249     3197      -52     
============================================
  Files           471      466       -5     
  Lines         10261    10089     -172     
  Branches       1805     1773      -32     
============================================
- Hits           8647     8485     -162     
- Misses          664      673       +9     
+ Partials        950      931      -19     

Impacted Files	Coverage Δ
...tekt/rules/exceptions/TooGenericExceptionThrown.kt	50.00% <0.00%> (-45.84%)	⬇️
...gitlab/arturbosch/detekt/rules/KtCallExpression.kt	0.00% <0.00%> (-33.34%)	⬇️
...osch/detekt/rules/style/CollapsibleIfStatements.kt	81.25% <0.00%> (-11.61%)	⬇️
...itlab/arturbosch/detekt/api/internal/Signatures.kt	77.55% <0.00%> (-8.17%)	⬇️
...s/performance/UnnecessaryTemporaryInstantiation.kt	78.57% <0.00%> (-6.05%)	⬇️
...gitlab/arturbosch/detekt/cli/ArgumentConverters.kt	69.23% <0.00%> (-5.77%)	⬇️
...rbosch/detekt/rules/style/UntilInsteadOfRangeTo.kt	77.77% <0.00%> (-3.18%)	⬇️
...itlab/arturbosch/detekt/rules/style/MagicNumber.kt	88.17% <0.00%> (-3.04%)	⬇️
...h/detekt/rules/naming/InvalidPackageDeclaration.kt	93.75% <0.00%> (-2.68%)	⬇️
...sch/detekt/rules/style/UnnecessaryAbstractClass.kt	82.60% <0.00%> (-2.18%)	⬇️
... and 49 more

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[3flex]

Till we wait for that, could we bump actions/setup-java only?

Created #4194 with the changes that aren't blocked by gradle-build-action@v2.

I still suggest not merging this one until gradle-build-action@v2 stable version is released (they're at beta 6 now so you'd think they're close - I'm subscribed to release notifications on that repo so I'll update here once it's good to go).

[cortinico]

Waiting for gradle/gradle-build-action@2.0. Just saw that RC1 got released one hour ago.

[3flex]

🎉

https://github.com/gradle/gradle-build-action/releases/tag/v2.0.0

[3flex]

An issue I've experienced with this implementation: gradle/gradle-build-action#120

Hopefully this is caught by the action in future. I don't think it's worth rolling back; it's not typical to have several jobs running concurrently. We might also try only caching on main branch: https://github.com/gradle/gradle-build-action/blob/v2.0.0/README.md#only-write-to-the-cache-from-the-default-branch

This would avoid many uploads occurring at once thanks to multiple PRs being opened quickly one after the other, but it would still occur when multiple PRs are merged quickly one after the other on main branch.