Reflection: add KTypeParameter.toString

The test covers different type parameters with and without bounds, in case we
decide to also output upper bounds in toString

compiler/testData/codegen/box/reflection/methodsFromAny/typeParametersToString.kt

@@ -0,0 +1,15 @@
+// WITH_REFLECT
+
+import kotlin.test.assertEquals
+
+interface Variance<A, in B, out C, D>
+class OneBound<T : Enum<T>>
+class SeveralBounds<T : Cloneable> where T : Enum<T>, T : Variance<String, Int?, Double?, Number>
+
+fun box(): String {
+    assertEquals("[A, in B, out C, D]", Variance::class.typeParameters.toString())
+    assertEquals("[T]", OneBound::class.typeParameters.toString())
+    assertEquals("[T]", SeveralBounds::class.typeParameters.toString())
+
+    return "OK"
+}