HLA-935: Update HDRTAB for MVM Products

[s-goldman]

Resolves HLA-935

This PR adds two new header keywords to MVM drizzled (drc/z) products. These include the name (SVMINPUT) and creation date (DATE-SVM) of each of the SVM images included within the MVM. These are inserted into the zeroth extension header for each of the filter-level products. These are listed high up in the header table (as requested) and can be fairly long (see image). The names and location of these keywords can easily be altered.

TODO: I'm still working on some unit tests for this code using unnittest.mock, but the requirement that a file has to be opened has made this challenging. I will likely use the sample_svm files within the test/hap directory.

Checklist for maintainers

• added entry in CHANGELOG.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR

[codecov]

Codecov Report

Attention: Patch coverage is 78.04878% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 31.76%. Comparing base (76a3e27) to head (69f00db).

Files	Patch %	Lines
drizzlepac/haputils/processing_utils.py	70.83%	7 Missing ⚠️
drizzlepac/hapmultisequencer.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1796      +/-   ##
==========================================
- Coverage   33.31%   31.76%   -1.55%     
==========================================
  Files         126      160      +34     
  Lines       31197    35203    +4006     
  Branches     5772        0    -5772     
==========================================
+ Hits        10392    11182     +790     
- Misses      19642    24021    +4379     
+ Partials     1163        0    -1163     

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[mdlpstsci]

This HLA-935 ticket has been misinterpreted. Please see the Jira ticket for an explanation.