Render flexible types with enhancement as enhanced in IDE (KT-25622)

Main targets for the fix is completion, parameters info, inlay hints and
override/implement.

Other IDE functions might be affected.

 #KT-24911 Fixed
 #KT-25616 Fixed
 #KT-25622 Fixed

idea/testData/parameterInfo/functionCall/Nullability.kt

@@ -3,5 +3,5 @@ fun test() {
 }
 
 /*
-Text: (<highlight>s1: String?</highlight>, s2: String, a: String!, b: String!, s3: String!), Disabled: false, Strikeout: false, Green: true
+Text: (<highlight>s1: String?</highlight>, s2: String, a: String?, b: String, s3: String!), Disabled: false, Strikeout: false, Green: true
 */