[PM-15061] extract encryptors from generator service

[audreyality]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-15061

📔 Objective

Extract encryptors from generator service so they can be reused across the tools codebase.

🦖 System Evolution

A new set of encryptors that distinguishes key slots from key instances is in the works. These encryptors also have specialized key rotation interfaces to enable integration with key services.

This PR introduces a parallel set of interfaces (LegacyEncryptorProvider et. al.) as a step towards that new system. Like the legacy generator services before it, the legacy encryptor interfaces arrive deprecated so that the impact of importing them is clear--porting to the new interfaces will be required once they become available.

🦮 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 79.56204% with 28 lines in your changes missing coverage. Please review.

Project coverage is 33.53%. Comparing base (7d6da0a) to head (332df67).
Report is 4 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
libs/common/src/tools/state/user-state-subject.ts	56.09%	16 Missing and 2 partials ⚠️
.../core/src/services/credential-generator.service.ts	61.53%	5 Missing ⚠️
libs/common/src/tools/state/object-key.ts	25.00%	3 Missing ⚠️
...rc/tools/cryptography/legacy-encryptor-provider.ts	0.00%	1 Missing ⚠️
...ols/send/send-ui/src/send-form/send-form.module.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12068      +/-   ##
==========================================
+ Coverage   33.47%   33.53%   +0.05%     
==========================================
  Files        2878     2882       +4     
  Lines       89941    90022      +81     
  Branches    17116    17125       +9     
==========================================
+ Hits        30106    30186      +80     
- Misses      57455    57456       +1     
  Partials     2380     2380              

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[djsmith85]

@audreyality Just some documentation updates and thank you for answering any questions I had offline.

[quexten]

Looks good from my side.