Add support for custom hooks
Some tools require to be built against the current Nim version, one example of this is `nimlsp` which will give error messages for the version of Nim it is built with. It would be nice if `choosenim` had some system by which you could add custom scripts to be run when changing version or installing a new one. This way tools like `nimlsp` could automatically match up with the version of Nim currently being used.

The feature should be fairly simple to implement, simply create a folder named hooks, with subfolders for each hook. Then simply run all the scripts in each folder when that action is triggered within the program.