Move compiler scripting tests to scripting plugin, remove unused funs

also remove some tests that are covered in the scripting-compiler
tests now.
Part of the cleanup to rewrite scripting to the new infrastructure.

plugins/scripting/scripting-compiler/testData/compiler/nullable_projection.kts

@@ -0,0 +1,5 @@
+import java.lang.RuntimeException
+
+val v: String? = param[0]
+
+if (v == null) System.out.println("nullable") else RuntimeException("non nullable projection")