feat(ui): room_list_service::filters::unread becomes read_receipts

[Hywan]

This patch renames the room_list_service::filters::unread filter to read_receipts and adds a new parameter: ReadReceiptsCategory. Before it was looking at the ReadReceipts::num_notifications field only, now it can look at the following field: num_mentions, num_notifications or num_messages.

The condition where Room::is_marked_unread makes the room to be selected if there is no unread is kept because (i) it's a manual operation from the user, (ii) it signals the room is unread but for an unknown reason, it could be anything, so it's important and should be displayed regardless of the number of unread.

Before:

filters::unread()

After:

filters::read_receipts(filters::ReadReceiptsCategory::Notifications)

It is admittedly a bit longer but it unlocks more flexibility and more features.

---

• Replace feat(ui): add a room list filter for rooms with unread mentions #6754, it applies the suggestions in feat(ui): add a room list filter for rooms with unread mentions #6754 (review)
• Address Room list has no way to filter on mentions element-hq/element-x-ios#3952
• Address Add a Mentions room list filter element-hq/element-x-ios#5885
• Address Add a Mentions room list filter element-hq/element-x-android#7211

---

• I've documented the public API changes in the appropriate changelog files (see Writing changelog entries).
• This PR was made with the help of AI.

Signed-off-by:

[codecov]

Codecov Report

❌ Patch coverage is 94.66667% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.11%. Comparing base (1d4bc12) to head (fe800e4).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...-ui/src/room_list_service/filters/read_receipts.rs	92.72%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6928      +/-   ##
==========================================
- Coverage   90.12%   90.11%   -0.01%     
==========================================
  Files         407      407              
  Lines      115985   115968      -17     
  Branches   115985   115968      -17     
==========================================
- Hits       104532   104506      -26     
- Misses       7535     7536       +1     
- Partials     3918     3926       +8     

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[codspeed-hq]

Merging this PR will not alter performance

✅ 50 untouched benchmarks

---

_{Comparing Hywan:feat-ui-room-list-filter-read-receipts (fe800e4) with main (0f4d63b)}

[poljar]

I left a couple of nits, looks good otherwise.