[PM-26803] Show empty state when no items are available for export

[SaintPatrck]

🎟️ Tracking

PM-26803

📔 Objective

This commit introduces an empty state for the "Review Export" screen, which is displayed when there are no vault items available for export. This can occur if the vault is empty or if the item types are not supported for export.

When this empty state is shown, the user is presented with two options:

• "Select a different account": This navigates the user back to the account selection screen.
• "Cancel": This cancels the export process and completes the flow with a cancellation result.

Specific changes:

• Updated ReviewExportViewModel to introduce a ViewState sealed class with Content and NoItems states. The view model now determines which state to show based on whether there are items to export.
• Modified ReviewExportScreen to display a BitwardenEmptyContent composable when the state is NoItems.
• Added a "Select a different account" button to the empty state, which triggers navigation back to the account selection screen.
• Updated the "Cancel" button's behavior to complete the export with an ImportCredentialsCancellationException result.
• Added new string resources for the empty state's title, text, and button labels.
• Expanded ReviewExportViewModelTest and ReviewExportScreenTest to cover the new empty state and navigation logic.

📸 Screenshots

⏰ 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

[github-actions]

Checkmarx One – Scan Summary & Details – a49ad017-fa66-47a4-9e29-ffadf14e1213

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

[codecov]

Codecov Report

❌ Patch coverage is 89.83051% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.59%. Comparing base (912eba1) to head (a199d66).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
.../exportitems/reviewexport/ReviewExportViewModel.kt	81.48%	2 Missing and 3 partials ⚠️
...ure/exportitems/reviewexport/ReviewExportScreen.kt	96.55%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6023   +/-   ##
=======================================
  Coverage   84.59%   84.59%           
=======================================
  Files         722      722           
  Lines       54897    54958   +61     
  Branches     7581     7592   +11     
=======================================
+ Hits        46440    46494   +54     
- Misses       5800     5801    +1     
- Partials     2657     2663    +6     

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