* Adds an IS_CHANGELING helper (#81228)
## About The Pull Request
What it says on the tin. I also replaced checks with it everywhere I
found appropriate, hopefully without accidentally breaking anything.
## Why It's Good For The Game
We have a helper for most other antags, and it makes code a lot cleaner
and easier to read. I'm surprised we didn't have this one already.
## Changelog
🆑
code: added an IS_CHANGELING() helper and used it where applicable
/🆑
* Adds an IS_CHANGELING helper
* skyrat stuff
---------
Co-authored-by: A miscellaneous Fern <80640114+FernandoJ8@users.noreply.github.com>
Co-authored-by: jjpark-kb <mccorvey.norman@gmail.com>
362362ec2c