Refactor so detekt-gradle-plugin can be added as an included build

[3flex]

This refactors the build logic so it's possible to include detekt-gradle-plugin as either a composite build or a standard project module. Just replace include("detekt-gradle-plugin") with includeBuild("detekt-gradle-plugin") in settings.gradle.kts to define the composite build.

[codecov]

Codecov Report

Merging #4094 (ced2e28) into main (e05eec5) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #4094      +/-   ##
============================================
- Coverage     83.45%   83.44%   -0.01%     
+ Complexity     3185     3177       -8     
============================================
  Files           463      465       +2     
  Lines          9095     9104       +9     
  Branches       1768     1775       +7     
============================================
+ Hits           7590     7597       +7     
- Misses          571      572       +1     
- Partials        934      935       +1     

Impacted Files	Coverage Δ
.../arturbosch/detekt/rules/style/UseIsNullOrEmpty.kt	54.66% <0.00%> (-2.67%)	⬇️
...bosch/detekt/rules/complexity/LongParameterList.kt	83.33% <0.00%> (-1.12%)	⬇️
...otlin/io/gitlab/arturbosch/detekt/core/Analyzer.kt	80.95% <0.00%> (-0.30%)	⬇️
...ab/arturbosch/detekt/core/config/ValidateConfig.kt	100.00% <0.00%> (ø)
...tlab/arturbosch/detekt/rules/style/UseDataClass.kt	77.94% <0.00%> (ø)
...b/arturbosch/detekt/rules/naming/FunctionNaming.kt	100.00% <0.00%> (ø)
...tlab/arturbosch/detekt/rules/bugs/LateinitUsage.kt	90.00% <0.00%> (ø)
...sch/detekt/rules/style/UnnecessaryAbstractClass.kt	82.92% <0.00%> (ø)
...etekt/rules/style/FunctionOnlyReturningConstant.kt	94.87% <0.00%> (ø)
...ch/detekt/core/suppressors/AnnotationSuppressor.kt	90.00% <0.00%> (ø)
... and 3 more

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[3flex]

Converting to draft as there's more to be done before this works as advertised.

[3flex]

I'm not loving the fact that some of the build config had to move back to the root project's build file instead of a precompiled script plugin in build-logic, but it wouldn't work as a composite build without it.

[3flex]

LGTM? I think this is as good as it will get.

I'm using these commits and a composite build myself for a couple of things and it's working really well.

[BraisGabin]

To be honest I'm a bit lost here. So I give my approve because it seems to work.

[BraisGabin]

We are moving this here because we can't apply this in the gradle plugin when we use composite compilation, right?

Could we create another plugin in build-logic so we don't need to have this here?

[3flex]

I'd moved it out of build-logic as it wasn't shared build config like mostly everything else that remained, but there's a home for it in releasing so I've moved it there instead. The config only needs to be applied to the root build file, and releasing is only applied in the root file so this makes sense to me.

[BraisGabin]

Why we can't keep this here?

[3flex]

When detekt-gradle-plugin is an included build, and it includes build-logic, the project dependencies can't be resolved. So they need to be moved out of build-logic - and applying them to subprojects from the root build file is the best way to do that from a single location.

[cortinico]

Just replace include("detekt-gradle-plugin") with includeBuild("detekt-gradle-plugin") in settings.gradle.kts to define the composite build.

Is there a reason why you haven't replaced this? That would allow us to don't have to rely on the preivously released version of detekt-gradle-plugin for the release and so on. Or are you afraid of a performance impact of the composite build?

[3flex]

I'm not too worried about perf personally, but I think some others are or were.

There's also the issue that running, for example, gradlew build in the root project won't execute the detekt-gradle-plugin:build task without wiring things up as described here: https://docs.gradle.org/current/userguide/composite_builds.html#included_build_task_dependencies

A separate PR could be opened to link up the lifecycle tasks (build, check, run) to the same tasks in the included build so it works as expected.