On packfile upload, use acquisition timestamp and subject code to find containers

[nagem]

If acquisition timestamp and/or subject code are provided in the request payload metadata, use this information to be more specific in the query to find an existing container.

This fixes an issue where files with the same acquisition name but different timestamps ended up in the same container when they should be separate containers.

This also fixes an issue if two sessions with the same label but different subject codes are uploaded.

Review Checklist

• Tests were added to cover all code changes
• Documentation was added / updated
• Code and tests follow standards in CONTRIBUTING.md

[nagem]

Writing tests for situations noted above, look for those soon.

[codecov-io]

Codecov Report

Merging #1066 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1066      +/-   ##
==========================================
+ Coverage   91.18%   91.19%   +0.01%     
==========================================
  Files          50       50              
  Lines        6920     6931      +11     
==========================================
+ Hits         6310     6321      +11     
  Misses        610      610