Track deleted files on disk

[HendricksJudy]

Fixes #83

Add functionality to track and remove deleted or moved files from the download list.

• File Watcher Implementation:

  • Add a file watcher in desktop/app/src/main/kotlin/com/abdownloadmanager/desktop/pages/home/HomeComponent.kt to detect file deletions or movements.
  • Implement logic to handle file events and remove affected files from the download list.
  • Register download directories for file watching.

• Download Manager Updates:

  • Add a file watcher in downloader/core/src/main/kotlin/ir/amirab/downloader/DownloadManager.kt to detect file deletions or movements.
  • Implement logic to handle file events and remove affected files from the download list.
  • Register download directories for file watching.

• Database Changes:

  • Add a method in downloader/core/src/main/kotlin/ir/amirab/downloader/db/IDownloadListDb.kt to get the file path of a download item by its ID.
  • Implement the method in downloader/core/src/main/kotlin/ir/amirab/downloader/db/MemoryDownloadListDB.kt.

• Download Destination Updates:

  • Add a method in downloader/core/src/main/kotlin/ir/amirab/downloader/destination/DownloadDestination.kt to check if the output file exists and is valid.
  • Implement the method in downloader/core/src/main/kotlin/ir/amirab/downloader/destination/SimpleDownloadDestination.kt.