Remove default import "kotlin.reflect"

Basic reflection is usable without any imports (with :: literals)

This reverts commit 9503056dd5.

compiler/testData/diagnostics/testsWithStdLib/callableReference/function/extensionOnNullable.kt

@@ -1,3 +1,5 @@
+import kotlin.reflect.*
+
 class A {
     fun foo() {}
 }