[backend/frontend] login aside panel customization (#14115)

[esrevi]

Proposed changes

Add new theme vars in Theme to handle customisation of the aside right panel on login
Add new section in Theme creation, update drawer to be able to add a color, or a gradient color, or an image url or base64

Related issues

• Custom Right-Hand Side Background Image #14115

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

[codecov]

Codecov Report

❌ Patch coverage is 17.54386% with 94 lines in your changes missing coverage. Please review.
✅ Project coverage is 32.35%. Comparing base (1fb52ee) to head (b248a14).
⚠️ Report is 13 commits behind head on master.

Files with missing lines	Patch %	Lines
...c/private/components/settings/themes/ThemeForm.tsx	0.00%	39 Missing ⚠️
...-front/src/public/components/login/LoginLayout.tsx	0.00%	15 Missing ⚠️
...vate/components/settings/themes/themeValidation.ts	0.00%	11 Missing ⚠️
.../opencti-graphql/src/modules/theme/theme-domain.ts	50.00%	8 Missing ⚠️
...rivate/components/settings/themes/ThemeEdition.tsx	0.00%	6 Missing ⚠️
.../private/components/settings/themes/theme-utils.ts	0.00%	6 Missing ⚠️
...ivate/components/settings/themes/ThemeCreation.tsx	0.00%	5 Missing ⚠️
...encti-graphql/src/modules/theme/theme-converter.ts	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14648      +/-   ##
==========================================
- Coverage   32.36%   32.35%   -0.01%     
==========================================
  Files        3096     3097       +1     
  Lines      210896   211142     +246     
  Branches    38196    38297     +101     
==========================================
+ Hits        68259    68318      +59     
- Misses     142637   142824     +187     

Flag	Coverage Δ
opencti-client-python	45.50% <ø> (ø)
opencti-front	2.83% <0.00%> (+<0.01%)	⬆️
opencti-graphql	67.73% <62.50%> (-0.01%)	⬇️

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