Set UsesKotlinJavaToolchain interface to extend Task interface.

Limit use-case of UsesKotlinJavaToolchain interface to only Gradle tasks
and allow to query all tasks using
 'taskContainer.withType(UsesKotlinJavaToolchain.class)'.

^KT-43095 In Progress

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/UsesKotlinJavaToolchain.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.gradle.tasks
 
 import org.gradle.api.JavaVersion
+import org.gradle.api.Task
 import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.Internal
@@ -14,7 +15,7 @@ import org.gradle.jvm.toolchain.JavaLauncher
 import org.gradle.util.GradleVersion
 import java.io.File
 
-interface UsesKotlinJavaToolchain {
+interface UsesKotlinJavaToolchain : Task {
     @get:Nested
     val kotlinJavaToolchainProvider: Provider<out KotlinJavaToolchain>