Display name disambiguation #2215.

Applied to:
- timeline message
- detail of timeline message
- reply preview of timeline message
- rendering of state Event
Not applied to:
- room last message
- room member list (we display the MatrixId here)
- room member detail page

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/ProfileTimelineDetails.kt

@@ -17,6 +17,7 @@
 package io.element.android.libraries.matrix.api.timeline.item.event
 
 import androidx.compose.runtime.Immutable
+import io.element.android.libraries.matrix.api.core.UserId
 
 @Immutable
 sealed interface ProfileTimelineDetails {
@@ -34,3 +35,20 @@ sealed interface ProfileTimelineDetails {
         val message: String
     ) : ProfileTimelineDetails
 }
+
+/**
+ * Returns a disambiguated display name for the user.
+ * If the display name is null, or profile is not Ready, the user ID is returned.
+ * If the display name is ambiguous, the user ID is appended in parentheses.
+ * Otherwise, the display name is returned.
+ */
+fun ProfileTimelineDetails.getDisambiguatedDisplayName(userId: UserId): String {
+    return when (this) {
+        is ProfileTimelineDetails.Ready -> when {
+            displayName == null -> userId.value
+            displayNameAmbiguous -> "$displayName ($userId)"
+            else -> displayName
+        }
+        else -> userId.value
+    }
+}