[PM-13362] Add private key regeneration endpoint

[Thomas-Avery]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-13362

📔 Objective

The purpose of this PR is to add an endpoint to enable private key regeneration for the clients on login and unlock.
This is feature will be behind a feature flag.

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) 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

[codecov]

Codecov Report

Attention: Patch coverage is 94.66667% with 4 lines in your changes missing coverage. Please review.

Project coverage is 43.17%. Comparing base (d88a103) to head (2927a26).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nt/Commands/RegenerateUserAsymmetricKeysCommand.cs	88.88%	0 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4929      +/-   ##
==========================================
+ Coverage   43.00%   43.17%   +0.17%     
==========================================
  Files        1447     1451       +4     
  Lines       66164    66239      +75     
  Branches     6062     6070       +8     
==========================================
+ Hits        28455    28601     +146     
+ Misses      36427    36352      -75     
- Partials     1282     1286       +4     

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[github-actions]

Checkmarx One – Scan Summary & Details – a6ed0368-2fdd-4a91-ab8a-2a0d41115d0e

New Issues

Severity	Issue	Source File / Package	Checkmarx Insight
	CSRF	/src/Api/Auth/Controllers/AccountsController.cs: 967	Attack Vector
	CSRF	/src/Api/KeyManagement/Controllers/AccountsKeyManagementController.cs: 37	Attack Vector
	Log_Forging	/src/Api/Auth/Controllers/AccountsController.cs: 967	Attack Vector
	Missing_CSP_Header	/src/Core/MailTemplates/Handlebars/AdminConsole/DomainClaimedByOrganization.html.hbs: 5	Attack Vector

Fixed Issues

Severity	Issue	Source File / Package
	CSRF	/src/Api/AdminConsole/Controllers/PoliciesController.cs: 70
	CSRF	/src/Billing/Controllers/RecoveryController.cs: 38
	CSRF	/src/Billing/Controllers/StripeController.cs: 164
	CSRF	/src/Api/AdminConsole/Controllers/PoliciesController.cs: 91
	CSRF	/src/Api/Auth/Controllers/AccountsController.cs: 470

The base branch was changed.