ES-295: Save Lab metadata in IDE files

[StokesMIDE]

This implements a mechanism for reading and writing user data in an .IDE file. Several new elements have been added to the schema for this purpose. The specific child elements of <UserData> may undergo revision.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.55556% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 74.60%. Comparing base (6420d42) to head (656de45).

Files	Patch %	Lines
idelib/userdata.py	84.88%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #149      +/-   ##
===========================================
+ Coverage    74.28%   74.60%   +0.32%     
===========================================
  Files           10       11       +1     
  Lines         3691     3781      +90     
===========================================
+ Hits          2742     2821      +79     
- Misses         949      960      +11     

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[ethandcosta]

looks good to me! As far as I can tell there shouldn't be streaming issues, but I could be missing things.

[pscheidler]

Really glad to see those tests in. This is too deep for me to do a thorough review