Deprecation of legacy script commands

Marking some legacy script commands as deprecated, for future removal.

***NOTE: This is a work in progress, please NO NOT merge.***

Goals of the project:

- Discourage the use in new scripts of certain legacy script commands that would promote bad scripting habits.
- Press users to update their custom scripts to remove said commands.
- Provide user documentation on how to replace those commands from custom scripts.
- Prepare for the complete removal of those script commands.

Non goals:

- Prevent any existing scripts from working.
- Remove any script commands.

Commands slated for removal and suggested alternatives (list will be integrated with other commands)

- [ ] `menu` -> `select`, `prompt`
- [ ] `set` -> direct assignment (NOTE: This can't be done at the moment, as there are some edge cases where `set` is still necessary, unfortunately. We may provide a non-deprecated synonym for those edge cases.
- [ ] `checkquest` -> `questprogress` (NOTE: This requires a re-commit of 4ac673941714032ada6d26fb60936ec510bbe496)
- [ ] `goto`, `jump_zero` -> proper use of `if`, `while`, `for`, `switch`. A synonym for edge cases (and for internal use) might be provided.