crypto: Rename msk to master_key for consistency with the wider codebase

[andybalaam]

As suggested in #3590 (comment)

Part of #3543

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.31%. Comparing base (40343aa) to head (0449ca8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3677      +/-   ##
==========================================
- Coverage   84.32%   84.31%   -0.02%     
==========================================
  Files         258      258              
  Lines       26614    26614              
==========================================
- Hits        22442    22439       -3     
- Misses       4172     4175       +3     

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[bnjbvr]

Looks like this wasn't tested at all 👀 Bonus points if you add a test that reads and checks those values.

[poljar]

Thank you.

[poljar]

Looks like this wasn't tested at all 👀 Bonus points if you add a test that reads and checks those values.

It's unused as of now, it will become used as part of #3590, where it is also tested. It was spit out for easier review.

[andybalaam]

Looks like this wasn't tested at all 👀 Bonus points if you add a test that reads and checks those values.

Thank you for your diligence and ordinarily I would enthusiastically agree but see @poljar 's answer :-)

It is unfortunate that this change is so big that I needed to break it up in annoying ways. Maybe we could have found a better way to break it up that formed individual functional changes, but I couldn't find one when I tried.