J2K: coversion of specially mapped built-in methods + replacing "get" with "[]" where possible

j2k/testData/fileOrElement/nullability/NullableMethodDotAccess.kt

@@ -4,6 +4,6 @@ internal class C {
     }
 
     fun foo(): Int {
-        return getString(true)!!.length()
+        return getString(true)!!.length
     }
 }

j2k/testData/fileOrElement/nullability/NullableVariableDotAccess.kt

@@ -1,5 +1,5 @@
 fun foo(s: String?, b: Boolean): Int {
     if (s == null) println("null")
-    if (b) return s!!.length()
+    if (b) return s!!.length
     return 10
 }

j2k/testData/fileOrElement/nullability/autoNotNull.kt

@@ -1,7 +1,7 @@
 internal class A {
     fun foo(s: String?): Int {
         if (s != null) {
-            return s.length()
+            return s.length
         }
         return -1
     }