Add a Mentions room list filter (#5885)

* Add a Mentions room list filter

Adds a new filter chip to the room list that shows only rooms with
unread mentions, using the new mentions room list filter from the
Rust SDK (matrix-org/matrix-rust-sdk branch matthew/mentions-filter).

The SDK version needs bumping to a release that includes the new
filter kind before this can build against the released components.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Order the room list filters by expected usage

Move Favourites ahead of People and Rooms so the more commonly used
filters (Unreads, Mentions, Favourites) sit first in the chip row —
Rooms and Invites are used rarely enough that it's fine for them to
wrap off the side.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uk8aPxHn3BHCe52L226jdG

* update the SDK and use the appropriate rust filter types

* preview tests + app settings flag for mentions

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Mauro Romito <mauro.romito@element.io>

ElementX.xcodeproj/project.pbxproj

@@ -10813,7 +10813,7 @@
 			repositoryURL = "https://github.com/element-hq/matrix-rust-components-swift";
 			requirement = {
 				kind = exactVersion;
-				version = 26.08.27;
+				version = 26.09.01;
 			};
 		};
 		701C7BEF8F70F7A83E852DCC /* XCRemoteSwiftPackageReference "GZIP" */ = {

ElementX.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -1,5 +1,5 @@
 {
-  "originHash" : "20b091ffed1191ab205d228b4682ceec9698235e1d8eb82e9aba1703fc8e9f05",
+  "originHash" : "bcdaa8f9cef68194f84e2cedfc8f5b970018b430090e70cabca834140c3573a5",
   "pins" : [
     {
       "identity" : "compound-design-tokens",
@@ -167,8 +167,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/element-hq/matrix-rust-components-swift",
       "state" : {
-        "revision" : "13503ceebfa90f7cc3c0c5de6392fcc73d993570",
-        "version" : "26.8.27"
+        "revision" : "5aba7a6306b02e79157831e8e352a9a959003e5b",
+        "version" : "26.9.1"
       }
     },
     {