[PM-13396] Add support for legacy error response model in getToken

[SaintPatrck]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-13396

📔 Objective

This commit adds support for the legacy error response model returned by the getToken endpoint.

The legacy model uses lowercase keys for error messages, while the current model uses uppercase keys. This change ensures that the app can handle both models correctly.

Additionally, the unit tests were updated to cover the scenario where the server returns a legacy error response.

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed
  issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – 3e71eeeb-62a5-4b11-8798-9f924b767ec5

New Issues

Severity	Issue	Source File / Package	Checkmarx Insight
	Privacy_Violation	/app/src/main/java/com/x8bit/bitwarden/data/tools/generator/repository/utils/GeneratorRepositoryExtensions.kt: 11	Attack Vector
	Unpinned Actions Full Length Commit SHA	/crowdin-pull.yml: 26	Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release. Pinning to a particular SHA helps...
	Unpinned Actions Full Length Commit SHA	/crowdin-pull.yml: 26	Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release. Pinning to a particular SHA helps...
	Use_of_Hardcoded_Password	/app/src/main/java/com/x8bit/bitwarden/data/autofill/util/HtmlInfoExtensions.kt: 20	Attack Vector

Fixed Issues

Severity	Issue	Source File / Package
	Privacy_Violation	/app/src/main/java/com/x8bit/bitwarden/ui/auth/feature/completeregistration/CompleteRegistrationViewModel.kt: 349
	Privacy_Violation	/app/src/main/java/com/x8bit/bitwarden/ui/auth/feature/completeregistration/CompleteRegistrationViewModel.kt: 349
	Privacy_Violation	/app/src/main/java/com/x8bit/bitwarden/ui/auth/feature/completeregistration/CompleteRegistrationViewModel.kt: 241
	Unpinned Actions Full Length Commit SHA	/crowdin-pull.yml: 27

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.89%. Comparing base (083578e) to head (b55741a).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4112   +/-   ##
=======================================
  Coverage   88.89%   88.89%           
=======================================
  Files         436      436           
  Lines       37702    37702           
  Branches     5281     5281           
=======================================
  Hits        33515    33515           
  Misses       2342     2342           
  Partials     1845     1845           

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