Add message search within rooms

### Your use case

Description

Element X Desktop provides the ability to search for messages within a room. However, this functionality does not seem to be available in Element X Android.

It would be very useful to have the same message search functionality on Android, especially for rooms with a long message history.

Question

Are there any plans to implement message search within rooms in Element X Android?

If this feature is already planned or tracked in another issue, please feel free to link the relevant issue.

Expected behavior

Users should be able to open a room and search through its message history using keywords, similar to the functionality available in Element X Desktop.

### Have you considered any alternatives?

Description

Element X Desktop provides the ability to search for messages within a room. However, this functionality does not seem to be available in Element X Android.

It would be very useful to have the same message search functionality on Android, especially for rooms with a long message history.

Question

Are there any plans to implement message search within rooms in Element X Android?

If this feature is already planned or tracked in another issue, please feel free to link the relevant issue.

Expected behavior

Users should be able to open a room and search through its message history using keywords, similar to the functionality available in Element X Desktop.

### Additional context

_No response_

### Are you willing to provide a PR?

Yes

The issue names no files, tests, or Android entry point. Start by locating the room UI and message-history search implementation, then compare its behavior with Element X Desktop. Done means users can search a room's message history by keyword on Android, with behavior comparable to the Desktop feature.

Written by the indexing model from the issue text.