Add credentialSecret to snapshot model and update logic to use it

[knolleary]

Fixes #3644

Description

This adds credentialSecret to the snapshot model so we no longer depend on the parent of the snapshot existing. This makes it easier to reason about the snapshots as they get moved around.

The db migration will populate the new column with the appropriate value from with the Device or ProjectSettings tables. I've tested this migration in both sqlite and postgres.

I have looked at many of the pipeline tests that relate to snapshots. They checked the result had a credentials property, but didn't try to validate the value. I've updated the tests in a few places to validate the credentials are properly encrypted with the expected key.

I've also done various bits of manual testing with rollbacks, instance-assigned devices, app-assigned devices, pipeline deploys to instances and devices/device groups.

[knolleary]

Am going to spin up a test env to do some more pointing and clicking before we merge, but please continue the review of the code.

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 41.88%. Comparing base (830cef9) to head (8e5cf18).

Files	Patch %	Lines
...s/20240327-01-add-credentialSecret-to-snapshots.js	85.71%	1 Missing ⚠️
forge/routes/api/deviceLive.js	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3649      +/-   ##
==========================================
- Coverage   41.88%   41.88%   -0.01%     
==========================================
  Files         628      629       +1     
  Lines       24417    24413       -4     
  Branches     5977     5973       -4     
==========================================
- Hits        10228    10225       -3     
+ Misses      14189    14188       -1     

Flag	Coverage Δ
backend	78.58% <88.88%> (-0.02%)	⬇️
frontend	1.91% <0.00%> (+<0.01%)	⬆️

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[knolleary]

Hitting a postgres-only test failure. Can recreate locally on pg, but on sqlite. Investigating...

[knolleary]

Test fixed.

[Steve-Mcl]

code and tests read fine but i am pulling this branch for a quick run through.

[Steve-Mcl]

code review and local testing with app device and other instance snapshot deploys 👍

[Steve-Mcl]

@knolleary Approved. Had to update branch and so tests are re-running. Merge when tests pass.

[Steve-Mcl]

@knolleary now that #3645 is merged, we can merge this.

#3645 had migration "20240325-01-add-teamTypeScope-to-FlowTemplates.js" which has a date 2 days prior to this PR "20240327-01-add-credentialSecret-to-snapshots.js"

I've merged main to this and will merge as soon as tests pass unless you shout up

[knolleary]

@Steve-Mcl all good - thanks