Birdshot engineering re-rework (tgstation#83685)

## About The Pull Request
Went with a more traditional SM setup

![image](https://github.com/tgstation/tgstation/assets/96586172/78a92c8d-ff14-4d27-a87d-bfa482517e5b)

Engineers have their own designated area

![image](https://github.com/tgstation/tgstation/assets/96586172/b84af593-06ae-467d-be37-1307c5e8f228)
Atmos layout:

![image](https://github.com/tgstation/tgstation/assets/96586172/6893dc6d-4598-4b97-9efc-e99e44bafac6)
## Why It's Good For The Game
A lot of engineer mains have been complaining about Birdshot
engineering, including me.
Decided to go with a more traditional SM setup because SM is something
that can easily derail the round and shouldn't be different from the
standard as that increases our chances of delam.
Went with something special for Atmos because players that sit in atmos
are experts anyways and a non-standard setup shouldn't confuse them too
much.
Engineers didn't have a designated area.

All in all I hope this change will help make birdshot a more favored map
than it is right now.
## Changelog
:cl:
add: Changed the layout of birdshot engineering atmos and SM, added a
proper engineering storage area.
/:cl: