Refactor 'errors.py' -> 'exceptions.py'

[tjlaboss]

Is your feature request related to a problem? Please describe.

errors.py contains both warnings and errors. It should be given the more general name exceptions.py

Describe the solution you'd like

• Rename the file as-is
• Add a new errors.py that just imports everything from exceptions.py, possibly with a deprecation warning

Describe alternatives you've considered

Split into errors.py and warnings.py

[MicahGale]

Ok I checked, Warning does subclass Exception so pythonically this makes sense. My concern is that importing montepy.errors is definitely something a user may do i.e.:

try: 
    something_sketch
except montepy.errors.NumberCollisionException:
    pass

I'm thinking we do the latter due to this. I think montepy.errors should be documented as deprecated. I don't know if we need to raise a warning (probably FutureWarning) when users import this directly though. I don't see much risk in having both montepy.errors and montepy.exceptions around for awhile.