Script, IDE: tweak extract based refactorings to behave better in scripts

Fix not being able to invoke introduce variable for top level script expression
Prohibit introduce parameter and introduce property for scripts on top level
Basic test for introduce function (produces red code atm)

idea/testData/refactoring/introduceProperty/script/ClassInScript.kts.after

@@ -0,0 +1,6 @@
+// EXTRACTION_TARGET: property with initializer
+class A {
+    private val i = 1
+
+    fun f() = i
+}