Add possibility to call core functions in custom code and automate the import process

**Is your feature request related to a problem? Please describe.**
I often have the following workflow:

- I need a specific functionality from the core in my custom code
- So I browse through the core modules until I found what I need, and now I need to import the class into my custom class
- Currently, I'm now copying the fully qualified name of the class, include it manually in my constructor, initialize the property and then go to the spot where I actually need the functionality and call my found function.
- This is a lot of manual work...

**Describe the solution you'd like** (*)

It would be awesome to have some kind of automatic copy/paste functionality for this issue.
So I would love to have a custom copy shortcut, which I can use while I'm in the function which I want to import.
Then I go back to my custom class and paste it.
The class then gets automatically added to my constructor, the property is initialized and my function is directly called. This would save a lot of time.

No files, tests, or entry points are named. Begin by locating how the plugin handles custom shortcuts and PHP code generation, then define done as a shortcut that adds the selected core class to the custom class constructor, initializes its property, and inserts the function call.

Written by the indexing model from the issue text.