Downloader tweaks + taskbar progress bar

[Araxeus]

• Use metadata.image from song-info provider only if not sending imgUrl from front (fixes out of sync artwork)
  

  youtube-music/plugins/downloader/back.js

  Lines 51 to 56 in 6b88397

  	const songMetadata = currentMetadata.imageSrcYTPL ? // This means metadata come from ytpl.getInfo();
  	{
  	...currentMetadata,
  	image: cropMaxWidth(await getImage(currentMetadata.imageSrcYTPL))
  	} :
  	{ ...nowPlayingMetadata, ...currentMetadata };

• Gets the best artwork possible using UrlToJPG + cropMaxWidth (in downloader/utils)
  (UrlToJPG is needed because videoDetails?.thumbnails[-1] is not always presented in jpg format (webp throw errors) + can be of different sizes. so this function guarantee the highest resolution of artwork)
  (cropMaxWidth gets pixel perfect cropping for official music artwork, without it the artwork usually have just big margins filled with solid color)
• Dodge possible thrown errors + more accurate query selector for the "start radio" button in the popup menu:
  

  youtube-music/plugins/downloader/front.js

  Lines 44 to 47 in a8ac2c3

  	let videoUrl = getSongMenu()
  	?.querySelector('ytmusic-menu-navigation-item-renderer.iron-selected[tabindex="0"]')
  	?.querySelector("#navigation-endpoint")
  	?.getAttribute("href");

• Adds a taskbar progress bar when downloading single songs, this allows seeing download progress without the submenu open (already implemented for playlists)

[Araxeus]

videoDetails.media can only appear in data parsed from ytpl.getInfo()
(never from XHR, I shouldn't have added it here in the first place)

[Araxeus]

this function will 99.9% of the time:
return a maxresdefault webp converted to jpg (quite frequent with newer videos)
or return the original url (is jpg)

0.1% chance (might even be 0%)
to do more than 1 iteration over qualityList (will only happen if original doesn't contains .jpg or maxresdefault)

This was mostly coded this way to 100% guarantee a jpg url output

note that this function is only applicable to thumbnails from ytpl.getInfo and not from XMLHttpRequest (song-info provider), since they are stored in a different source and in completely different formats

[th-ch]

nit:

Suggested change

	module.exports.UrlToJPG = (imgUrl, videoId) => {
	module.exports.urlToJPG = (imgUrl, videoId) => {

[th-ch]

Just a nit but nothing blocking, otherwise looks good, thanks for the improvement, merging! ✅