Febus read, scan, and is_format support

[d-chambers]

Description

This PR adds support for the Febus DAS format.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes.
• documented the new feature with docstrings or appropriate doc page.
• included a test. See testing guidelines.
• your name has been added to the contributors page (docs/contributors.md).
• added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.53%. Comparing base (3b01269) to head (e6d4d29).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #369      +/-   ##
==========================================
+ Coverage   99.52%   99.53%   +0.01%     
==========================================
  Files          94       97       +3     
  Lines        7415     7596     +181     
==========================================
+ Hits         7380     7561     +181     
  Misses         35       35              

Flag	Coverage Δ
unittests	99.53% <100.00%> (+0.01%)	⬆️

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[d-chambers]

I am going to merge this for now so we can do a quick release before the SSA das session tomorrow.