Add ability to search, download, and delete external subtitles files

[1hitsong]

Changes

Creates the ability for admins to search, download, and delete external subtitles files directly from their Roku device.

A breakdown of how it works: https://forum.jellyfin.org/t-movie-remote-subtitle-management?pid=15714#pid15714

Note: for the search feature to work, you must have a provider setup. See my post here: https://forum.jellyfin.org/t-movie-remote-subtitle-management?pid=15806#pid15806

Issues

Fixes #1682

Multi-part phases

1. Core functionality for movies only ⬅️ This PR
2. Redesign movie detail page to improve UX
3. Add functionality for TV episodes

[jellyfin-bot]

This pull request has been inactive for 21 days and will be automatically closed in 7 days if there is no further activity.

[jellyfin-bot]

This pull request has been inactive for 21 days and will be automatically closed in 7 days if there is no further activity.

[jellyfin-bot]

This pull request has been closed because it has been inactive for 28 days. You may submit a new pull request if desired.