Fix class loading of classes that have property upgrades

[asodja]

We should be able to add instrumented projects as compileOnly dependencies of :instrumentation-declarations project, but that results in NoClassDefFoundError at runtime for upgraded types.

Let's figure out why that happens.

[asodja]

Reproducer:
https://github.com/gradle/gradle/compare/asodja/reproduce-classpath-issue?expand=1

Run any test in PropertyUpgradesBinaryCompatibilityCrossVersionSpec, you will see error like:

Caused by: org.gradle.api.internal.tasks.DefaultTaskContainer$TaskCreationException: Could not create task ':myCheckstyle'.
	at org.gradle.api.internal.tasks.DefaultTaskContainer.taskCreationException(DefaultTaskContainer.java:721)
Caused by: java.lang.NoClassDefFoundError: org/gradle/api/plugins/quality/Checkstyle
	at org.gradle.internal.classpath.generated.Checkstyle_Adapter.access_set_maxErrors(Checkstyle_Adapter.java:11)

Changing this line:

gradle/subprojects/instrumentation-declarations/build.gradle.kts

Line 16 in f98bfcd

compileOnly(project(":code-quality"))

to implementation(project(":code-quality")) should fix the problem. But that change should not be necessary.

[asodja]

Checkstyle_Adapter is loaded from VisitableURLClassLoader(ant-and-gradle-loader) and we then need also Checkstyle there.
While if we use compileOnly(project(":code-quality")) Checkstyle is loaded from MixInLegacyTypesClassLoader(legacy-mixin-loader).

So one solution, that might work for Java and Kotlin is, that we separate instrumentation code and adapters. So we would have one jar with classes like InterceptorDeclaration_PropertyUpgradesJvmBytecode and another one with actuall logic. Not sure if that works for Groovy.