[Test] Add debug names to unnamed test disposables

- This helps to track down disposables which are never disposed, and
  reduces confusion when printing disposables in general (the names will
  now be meaningful, instead of endless lists of "newDisposable" and
  "TestDisposable").

^KT-64099

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/ApplicationEnvironmentDisposer.kt

@@ -16,7 +16,7 @@ import java.lang.reflect.Field
 
 class ApplicationEnvironmentDisposer : TestExecutionListener {
     companion object {
-        val ROOT_DISPOSABLE: Disposable = Disposer.newDisposable()
+        val ROOT_DISPOSABLE: Disposable = Disposer.newDisposable("${ApplicationEnvironmentDisposer::class.simpleName}.ROOT_DISPOSABLE")
     }
 
     override fun testPlanExecutionFinished(testPlan: TestPlan) {

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/impl/TestConfigurationImpl.kt

@@ -50,7 +50,7 @@ class TestConfigurationImpl(
 
     val originalBuilder: TestConfigurationBuilder.ReadOnlyBuilder
 ) : TestConfiguration(), TestService {
-    override val rootDisposable: Disposable = TestDisposable()
+    override val rootDisposable: Disposable = TestDisposable("${TestConfigurationImpl::class.simpleName}.rootDisposable")
     override val testServices: TestServices = TestServices()
 
     init {

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/utils/TestDisposable.kt

@@ -7,7 +7,7 @@ package org.jetbrains.kotlin.test.utils
 
 import com.intellij.openapi.Disposable
 
-class TestDisposable : Disposable {
+class TestDisposable(val debugName: String) : Disposable {
     @Volatile
     var isDisposed = false
         private set
@@ -15,4 +15,6 @@ class TestDisposable : Disposable {
     override fun dispose() {
         isDisposed = true
     }
+
+    override fun toString(): String = debugName
 }