fix: e2ei identity certificate status (WPB-20235)

[sbakhtiarov]

https://wearezeta.atlassian.net/browse/WPB-20235

What's new in this PR?

Issue

When User A views User B's device details (both from the same team with E2EI enabled), the UI shows:

1. "Not activated" status in the E2EI certificate section
2. Red error icon next to the device name in OtherUserDevicesScreen and DeviceDetailsScreen

This happens even when User B has a valid E2EI certificate.

Cause

Users A and B only have Proteus conversations, no MLS conversations. E2EI identity lookup via CoreCrypto requires an MLS group ID, so when there's no common MLS conversation, the lookup fails with StorageFailure.DataNotFound.

Previously, all failures from GetMLSClientIdentityUseCase were treated the same, resulting in mlsClientIdentity = null. The UI then displayed this as "Not activated" with an error icon, which is incorrect - the E2EI data is simply unavailable, not "not activated".

Solution

Handle the E2EINotAvailable failure case separately and hide E2EI-related UI elements when E2EI identity data cannot be retrieved due to lack of common MLS conversation.

[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

[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

[codecov]

Codecov Report

❌ Patch coverage is 61.53846% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.64%. Comparing base (9d1ef9a) to head (ee6cfc7).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
...roid/ui/settings/devices/DeviceDetailsViewModel.kt	0.00%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4565      +/-   ##
===========================================
- Coverage    48.65%   48.64%   -0.01%     
===========================================
  Files          576      576              
  Lines        19942    19950       +8     
  Branches      3335     3336       +1     
===========================================
+ Hits          9702     9705       +3     
- Misses        9214     9218       +4     
- Partials      1026     1027       +1     

Files with missing lines	Coverage Δ
...i/home/newconversation/NewConversationViewModel.kt	69.54% <100.00%> (+0.35%)	⬆️
...id/ui/settings/devices/model/DeviceDetailsState.kt	100.00% <100.00%> (ø)
...roid/ui/settings/devices/DeviceDetailsViewModel.kt	68.42% <0.00%> (-2.68%)	⬇️

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