Custom extended themes

[Bonsai8863]

Proposed changes

• Added new Theme objects in backend, along with relevant resolvers and such
• Modified Settings page to allow admins to create, modify, export, and import custom themes
• Modified Settings page to allow admins to select default platform theme from a dynamic list
• Modified User profile page to select their preferred theme from a dynamic list
• Modified frontend theming to use dynamic themes instead of dark/light themes

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case (coverage and e2e)
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

Related to the discussion in #8239, we decided that a better solution would be to allow admins to customize the themes of the platform with greater granularity. This should eventually expand to more fields, such as text color.

[codecov]

Codecov Report

Attention: Patch coverage is 45.02370% with 116 lines in your changes missing coverage. Please review.

Project coverage is 64.48%. Comparing base (845adf3) to head (8bf7ba3).

Files with missing lines	Patch %	Lines
.../opencti-graphql/src/modules/theme/theme-domain.ts	24.00%	95 Missing ⚠️
...encti-graphql/src/modules/theme/theme-converter.ts	16.00%	21 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                @@
##           release/6.5.0    #9456      +/-   ##
=================================================
- Coverage          64.56%   64.48%   -0.08%     
=================================================
  Files                641      646       +5     
  Lines              61955    62166     +211     
  Branches            6888     6884       -4     
=================================================
+ Hits               39999    40087      +88     
- Misses             21956    22079     +123     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.