API, datastore, migration for new "user settings", with `"hidden_hosts_table_columns" setting

[jacobshandling]

For #25033

• For database migrations:
  • Checked schema for all modified table for columns that will auto-update timestamps during migration.
  • Confirmed that updating the timestamps is acceptable, and will not cause unwanted side effects.
• Added/updated automated tests
• A detailed QA plan exists on the associated ticket (if it isn't there, work with the product group's QA engineer to add it)
• Manual QA for all new/changed functionality

[codecov]

Codecov Report

Attention: Patch coverage is 56.16438% with 32 lines in your changes missing coverage. Please review.

Project coverage is 63.85%. Comparing base (cac3e2f) to head (8a4ec25).
Report is 39 commits behind head on main.

Files with missing lines	Patch %	Lines
server/datastore/mysql/users.go	54.83%	10 Missing and 4 partials ⚠️
server/service/users.go	60.86%	6 Missing and 3 partials ⚠️
...es/20250107165731_AddSettingsColumnToUsersTable.go	50.00%	4 Missing and 1 partial ⚠️
server/fleet/users.go	50.00%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #25184   +/-   ##
=======================================
  Coverage   63.85%   63.85%           
=======================================
  Files        1616     1617    +1     
  Lines      153833   153913   +80     
  Branches     3939     3939           
=======================================
+ Hits        98231    98283   +52     
- Misses      47789    47809   +20     
- Partials     7813     7821    +8     

Flag	Coverage Δ
backend	64.72% <56.16%> (+<0.01%)	⬆️

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[lucasmrod]

First pass looks good to me.

[lucasmrod]

Looks good, left some comments.