Search: include filenames of files uploaded in chat rooms in the search result

**Is your feature request related to a problem? Please describe.**

Yes, when searching for messages in the mobile app, the filenames of uploaded files in chat rooms are not displayed in the search results. This can be frustrating when trying to locate specific files that were shared in a conversation.

**Describe the solution you'd like**

I would like the mobile app’s search feature to include filenames of uploaded files in chat rooms, similar to the unified search in the web client. When a user searches in a chat room, the search results should display not only text messages but also the names of uploaded files.

**Additional context**

In the web client’s unified search, the results include files, making it easier to find shared documents (as shown in the attached screenshot). Including this capability in the mobile app would improve the overall user experience and ensure consistency across platforms.

ref to issue for Android app: nextcloud/talk-android#4286