Show video and audio thumbnail in Download Manager

[SameenAhnaf]

Checklist

• I checked, but didn't find any duplicates (open OR closed) of this issue in the repo.
• I have read the contribution guidelines given at https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md.
• This issue contains only one feature request. I will open one issue for every feature I want to request.

Describe the feature you want

Video thumbnail is not shown in download manager. It's a little frustrating. Sometimes, I have to deal with video titles like "Episode 65" and "Episode 66" which are slightly confusing although video thumbnail could solve the problems easily.

Is your feature request related to a problem? Please describe it

Additional context

How will you/everyone benefit from this feature?

[Stypox]

#5445