[PM-29842] Add organization event types for item migration acceptance and rejection

[SaintPatrck]

🎟️ Tracking

PM-29842
Relates to bitwarden/server#6721

📔 Objective

Introduce new organization event types to track user decisions regarding the migration of personal ciphers to an organization's "My Items" folder, typically triggered by personal vault ownership policies.

Actual event tracking will be implemented in a subsequent PR.

Specific changes:

• Update OrganizationEventType in the network layer to include ORGANIZATION_ITEM_ORGANIZATION_ACCEPTED (1618) and ORGANIZATION_ITEM_ORGANIZATION_DECLINED (1619).
• Add corresponding data objects ItemOrganizationAccepted and ItemOrganizationDeclined to the OrganizationEvent sealed class hierarchy to handle these events within the application logic.

⏰ 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

[claude]

Claude finished @SaintPatrck's task in 2m 24s —— View job

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Code Review Complete ✓

The review has been completed. All findings have been posted as inline comments and a summary review.

Status: Changes look good - the implementation correctly follows Bitwarden's established patterns for organization event types.

[github-actions]

Checkmarx One – Scan Summary & Details – a7c6e4a2-6fc8-4697-98ad-58047b04e569

Great job! No new security vulnerabilities introduced in this pull request

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.53%. Comparing base (d09945d) to head (15ac0cf).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

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  Coverage   85.53%   85.53%           
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  Files         761      761           
  Lines       54519    54519           
  Branches     7833     7833           
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  Hits        46633    46633           
  Misses       5169     5169           
  Partials     2717     2717           

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