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_parameter.kts

@@ -0,0 +1,4 @@
+import java.lang.RuntimeException
+
+val k: Int? = param
+if (k == null) System.out.println("Param is null") else throw RuntimeException("param is not null")