* GDScriptLanguage::complete_code already adds parentheses to function calls, and does this a lot smarter than the language server right now.
* Instead of the previous naive approach we now reuse the same logic as the internal editor.
* For this to have any effect we also have to send the `insertText` field already during the completionRequest and not only during resolve.
(cherry picked from commit bbb07ff8cb)
c07d1d0de8