Update Apple config/DDM profiles if secret variables changed

[getvictor]

#24900

This PR includes and depends on PR #25012, which should be reviewed/merged before this one.

Windows profiles are not included in this PR due to issue #25030

This PR adds the following functionality: Apple config/DDM profile is resent to the device when the profile contains secret variables, and the values of those variables have changed. For example.

• Upload secret variables
• Upload profile
• Device gets profile
• Upload the same profile
• Nothing happens
• Upload a different secret variable value
• Upload the same profile
• Device gets updated profile

Checklist for submitter

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information.
• Added/updated tests
• If database migrations are included, checked table schema to confirm autoupdate
• For database migrations:
  • Checked schema for all modified table for columns that will auto-update timestamps during migration.
• Manual QA for all new/changed functionality

[codecov]

Codecov Report

Attention: Patch coverage is 86.48649% with 30 lines in your changes missing coverage. Please review.

Project coverage is 63.83%. Comparing base (5f4400b) to head (b2bc9d0).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
server/datastore/mysql/secret_variables.go	78.57%	10 Missing and 5 partials ⚠️
...tions/tables/20241230000000_AddSecretsUpdatedAt.go	62.16%	10 Missing and 4 partials ⚠️
server/service/apple_mdm.go	91.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #24995   +/-   ##
=======================================
  Coverage   63.82%   63.83%           
=======================================
  Files        1613     1614    +1     
  Lines      153431   153516   +85     
  Branches     3985     4036   +51     
=======================================
+ Hits        97922    97991   +69     
- Misses      47716    47727   +11     
- Partials     7793     7798    +5     

Flag	Coverage Δ
backend	64.70% <86.48%> (+<0.01%)	⬆️

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[iansltx]

This looks reasonable. This is code I haven't touched before so my signoff is caveated with "this needs an airtight QA plan" but the new functionality and tweaks to existing (e.g. pushing checksums to the DB) make sense.