Provide calculated server names when opening a room from another (#5155)

* Provide calculated server names when opening a room from another, based on the most frequently used domain names in the user ids for the users in the room.

This helps when following permalinks or navigating to the successor room of a tombstoned one. Previously, the `/summary` endpoint was failing because no server names were used in the `via` parameters.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/core/UserId.kt

@@ -29,4 +29,7 @@ value class UserId(val value: String) : Serializable {
         get() = value
             .removePrefix("@")
             .substringBefore(":")
+
+    val domainName: String?
+        get() = value.substringAfter(":").takeIf { it.isNotEmpty() }
 }