Simplify File Selection in Add Track Form

When the file selection popup opens, we need to click the “Add” button to select a file. It would be much more intuitive if we could simply click on the filename itself to select it. The filename should be highlighted when the mouse hovers over it to indicate that it's the desired file.

Additionally, the "Add" button could be removed, leaving only the “Delete” button for removing files. This would simplify the process and make it quicker and more user-friendly.