[PM-21918] update send api models to support new email field

[audreyality]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-21918

📔 Objective

Update send API models to support email/OTP administration.

Important

This PR includes documentation for the related models. I mostly inferred what each of these are. Please focus on them during review to confirm that the comments are correct.

⏰ 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

[audreyality]

📝 This PR may wait to merge until the CLI logic is stable.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Checkmarx One – Scan Summary & Details – c9b0276d-80ee-4a06-8165-fbaeda4c5661

Great job, no security vulnerabilities found in this Pull Request

[codecov]

Codecov Report

Attention: Patch coverage is 12.50000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 47.50%. Comparing base (f3e637c) to head (2d625f6).
Report is 43 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Api/Tools/Models/Request/SendRequestModel.cs	16.66%	4 Missing and 1 partial ⚠️
src/Api/Tools/Models/Response/SendResponseModel.cs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5895      +/-   ##
==========================================
- Coverage   47.51%   47.50%   -0.01%     
==========================================
  Files        1662     1662              
  Lines       75215    75228      +13     
  Branches     6761     6763       +2     
==========================================
+ Hits        35737    35738       +1     
- Misses      38015    38026      +11     
- Partials     1463     1464       +1     

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