Refactor: regroup "gain control of [StackObject]" effects

I think at this time only spells can change controller that way?

https://scryfall.com/search?q=o%3A%2Fgain+control%5B%5E%2C.%5D*spell%2F+or+o%3A%2Fgain+control%5B%5E%2C.%5D*ability%2F&unique=cards&as=grid&order=name

Start with the linked Scryfall search to verify which cards use “gain control” effects involving spells or abilities. Then locate the corresponding effect implementations in the repository and determine how they should be regrouped; done means the relevant effects are organized consistently without changing their behavior.

Written by the indexing model from the issue text.