Add sidebar-tooltip stream previews

[Melonify]

Adds option to show thumbnail previews of streams when hovering over channels on the sidebar

[8thony]

For me its to small I want to have the option to increase this preview and the image quality.
I quickly tested this by setting the image quality to 1920x1080 and the box width to 100.
Note: if the browser window gets smaller, it should automatically decrease the preview box size otherwise it fills the entire window

[MaskedDuckling311]

a thumbnail size slider and a hover delay option would be great.
otherwise, the implementation looks clean.