## Summary
Desktop companion to https://invent.kde.org/kde/kdeconnect-android/merge_requests/78
Give desktop SMS app a basic understanding of the MMSes coming from Android:
- Show a fake body if we get an attachment we can't display (for now, any attachment)
- Display a fake contact header for multi-target messages since Android does not yet export multi-target address information
- Disable attempting to reply to multi-target messages
BUG: 398889
## Test Plan
### Before:
MMS messages were silently dropped, meaning:
- Group MMS conversations were not visible
- Single-target conversations with the most-recent message an MMS were not visible
### After:
- Install https://invent.kde.org/kde/kdeconnect-android/merge_requests/78
- Multi-target conversations are displayed (kind of ugly, since they have no contact information
- Single-target conversations which end with an MMS are displayed
- Plain-text MMS is displayed nicely
- MMS attachments don't show
- MMS which are only an attachment with no body are displayed with a dummy body
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