[Gradle] Opt in for the experimental build tools API module-wide

#KT-61449 In Progress

libraries/tools/kotlin-gradle-plugin/build.gradle.kts

@@ -31,6 +31,7 @@ kotlin {
                 "org.jetbrains.kotlin.gradle.ExternalKotlinTargetApi",
                 "org.jetbrains.kotlin.compiler.plugin.ExperimentalCompilerApi",
                 "org.jetbrains.kotlin.gradle.DeprecatedTargetPresetApi",
+                "org.jetbrains.kotlin.buildtools.api.ExperimentalBuildToolsApi",
             )
         )
         suppressWarnings = true

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/compilerRunner/btapi/BuildToolsApiCompilationWork.kt

@@ -39,7 +39,6 @@ private val ChangedFiles.asSourcesChanges: SourcesChanges
         is ChangedFiles.Unknown -> SourcesChanges.Unknown
     }
 
-@OptIn(ExperimentalBuildToolsApi::class)
 internal abstract class BuildToolsApiCompilationWork : WorkAction<BuildToolsApiCompilationWork.BuildToolsApiCompilationParameters> {
     internal interface BuildToolsApiCompilationParameters : WorkParameters {
         val buildIdService: Property<BuildIdService>
@@ -142,7 +141,6 @@ internal abstract class BuildToolsApiCompilationWork : WorkAction<BuildToolsApiC
         }
 }
 
-@OptIn(ExperimentalBuildToolsApi::class)
 internal object SharedApiClassesClassLoaderProvider : ParentClassLoaderProvider {
     override fun getClassLoader() = SharedApiClassesClassLoader()
 

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/internal/transforms/BuildToolsApiClasspathEntrySnapshotTransform.kt

@@ -14,7 +14,6 @@ import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.Classpath
 import org.gradle.api.tasks.Internal
 import org.jetbrains.kotlin.buildtools.api.CompilationService
-import org.jetbrains.kotlin.buildtools.api.ExperimentalBuildToolsApi
 import org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshotGranularity
 import org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshotGranularity.CLASS_LEVEL
 import org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshotGranularity.CLASS_MEMBER_LEVEL
@@ -24,7 +23,6 @@ import java.io.File
 
 /** Transform to create a snapshot of a classpath entry (directory or jar). */
 @CacheableTransform
-@OptIn(ExperimentalBuildToolsApi::class)
 abstract class BuildToolsApiClasspathEntrySnapshotTransform : TransformAction<BuildToolsApiClasspathEntrySnapshotTransform.Parameters> {
 
     abstract class Parameters : TransformParameters {