[Test] TestGen: Use canonical class names for generated imports

This is needed to have correct class names for inner/nested classes. For example, to have `import java.util.AbstractMap.SimpleEntry` instead of `import java.util.AbstractMap$SimpleEntry`.

compiler/tests-common/tests/org/jetbrains/kotlin/generators/impl/TestGeneratorImpl.kt

@@ -127,7 +127,7 @@ private class TestGeneratorImplInstance(
             val realName = when (clazz) {
                 TransformingTestMethodModel.TransformerFunctionsClassPlaceHolder::class.java ->
                     "org.jetbrains.kotlin.test.utils.TransformersFunctions"
-                else -> clazz.name
+                else -> clazz.canonicalName
             }
             p.println("import $realName;")
         }

generators/test-generator/tests/org/jetbrains/kotlin/generators/NewTestGeneratorImpl.kt

@@ -132,7 +132,7 @@ object NewTestGeneratorImpl : TestGenerator(METHOD_GENERATORS) {
                 val realName = when (clazz) {
                     TransformingTestMethodModel.TransformerFunctionsClassPlaceHolder::class.java ->
                         "org.jetbrains.kotlin.test.utils.TransformersFunctions"
-                    else -> clazz.name
+                    else -> clazz.canonicalName
                 }
                 p.println("import $realName;")
             }