Rename 'realtime_file_preview' to 'ai_similar_media' across module

Problem/Motivation

When I had developed this module, a poc was done on realtime file name preview below any file upload field and in the same module the work was continued. The name of the module is actually ai similar media but in the code everywhere there is realtime_file_preview.

Proposed resolution

Rename 'realtime_file_preview' and similar key words to 'ai_similar_media'.

User interface changes

There should be no change in the functionality of the UI of the module.