Add intention for replacing explicit function literal parameter with 'it'

Kotlin's function literals have a shortcut for one-argument literals:
the single argument doesn't need to be explicitly named, but can be
referred via the 'it' contextual keyword.

For example, 'array(1, 2, 3).filter { x -> x % 2 == 0 }'
          -> 'array(1, 2, 3).filter { it % 2 == 0 }'

Add an intention action for this transformation.

idea/testData/intentions/replaceExplicitFunctionLiteralParamWithIt/applicable_formatsProperly.kt

@@ -0,0 +1,6 @@
+fun foo(i: (Int) -> Unit) {}
+fun test() {
+    foo { <caret>x ->
+        array(1, 2, 3).filter { x -> x % 2 == 0 }
+    }
+}