Update metadata records format

[wtgee]

• Store one top-level document called metadata for each unit, with the specific sub-collection stored as a key name.
• Also create a document in the records collection for just the collection.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 70.40%. Comparing base (c0e6750) to head (e2f5748).
Report is 17 commits behind head on develop.

Files	Patch %	Lines
src/panoptes/pocs/utils/cli/network.py	0.00%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1269      +/-   ##
===========================================
+ Coverage    70.39%   70.40%   +0.01%     
===========================================
  Files          100      100              
  Lines         8423     8423              
  Branches      1170     1170              
===========================================
+ Hits          5929     5930       +1     
  Misses        2343     2343              
+ Partials       151      150       -1     

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