JP-3223: Extract_2d 'slit_name' parameter fails for NRS_MSASPEC slits

[penaguerrero]

Resolves JP-3223

Closes #7865

This PR addresses a crash of Spec2 when the parameter slit_name was provided as integer for MOS data. The pipeline now expects a string for this value, and the extract_2d code will make the corresponding value type conversions to make sure that both values in the comparison are the same type.
The documentation was modified to explain that for MOS data the value is expected as a string, e.g. slit_name='67'

Checklist for maintainers

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• Make sure the JIRA ticket is resolved properly

[codecov]

Codecov Report

Attention: 12 lines in your changes are missing coverage. Please review.

Comparison is base (5b63bda) 75.95% compared to head (cb327aa) 75.93%.

Files	Patch %	Lines
jwst/extract_2d/nirspec.py	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8081      +/-   ##
==========================================
- Coverage   75.95%   75.93%   -0.03%     
==========================================
  Files         459      459              
  Lines       37597    37608      +11     
==========================================
  Hits        28557    28557              
- Misses       9040     9051      +11     

Flag	Coverage Δ		*Carryforward flag
nightly	77.37% <ø> (+<0.01%)	⬆️	Carriedforward from 47f8771

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[penaguerrero]

The regrets ran successfully, though there are differences with the truth files, results are here: https://plwishmaster.stsci.edu:8081/job/RT/job/JWST-Developers-Pull-Requests/1055/#showFailuresLink

[hbushouse]

The regrets ran successfully, though there are differences with the truth files, results are here: https://plwishmaster.stsci.edu:8081/job/RT/job/JWST-Developers-Pull-Requests/1055/#showFailuresLink

Yes, those failures are unrelated (due to a recent ref file update). I wouldn't expect any changes in output from this PR, since it involves a user-specified input param.

[hbushouse]

Looks good to me.