[Feature] Subtitle offset

[teijiIshida]

Is your feature request related to a problem? Please describe.
When viewing JAV scenes with subtitles (downloaded from various sources or Whisper generated), sometimes the subtitle isn't in sync.

Describe the solution you'd like
Add a way to offset subtitle in both negative and positive time. For example, normal sub would be at 0. A negative -500 ms would make the sub display earlier by 500ms. A positive +500 ms would delay the sub by 500 ms. And it'd be nice to add hotkeys for those too to change it fast on-the-fly. Lastly, Stash should remember the offset of each videos, so user doesn't have to change it every time they open the same video.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.