Add runtime provider for `plugin-annotations`

[kyay10]

Otherwise, testData files might reference functions from the annotation lib, but then fail at runtime during testing.

Here's how I've done it (I'll open a PR soon enough):

import org.jetbrains.kotlin.cli.jvm.config.addJvmClasspathRoots
import org.jetbrains.kotlin.config.CompilerConfiguration
import org.jetbrains.kotlin.test.model.TestModule
import org.jetbrains.kotlin.test.services.EnvironmentConfigurator
import org.jetbrains.kotlin.test.services.RuntimeClasspathProvider
import org.jetbrains.kotlin.test.services.TestServices
import java.io.File

class PluginAnnotationsProvider(testServices: TestServices) : EnvironmentConfigurator(testServices) {
  companion object {
    val annotationsRuntimeClasspath =
      System.getProperty("annotationsRuntime.classpath")?.split(File.pathSeparator)?.map(::File)
        ?: error("Unable to get a valid classpath from 'annotationsRuntime.classpath' property")
  }

  override fun configureCompilerConfiguration(configuration: CompilerConfiguration, module: TestModule) {
    configuration.addJvmClasspathRoots(annotationsRuntimeClasspath)
  }
}

class PluginRuntimeAnnotationsProvider(testServices: TestServices) : RuntimeClasspathProvider(testServices) {
  override fun runtimeClassPaths(module: TestModule) = PluginAnnotationsProvider.annotationsRuntimeClasspath
}

then in AbstractJvmBoxTest.configure, I added:

useCustomRuntimeClasspathProviders(::PluginRuntimeAnnotationsProvider)

[bnorm]

Good catch. We do the first part, but not the second. A PR would be welcome.