feat: newgrounds video & audio support

[hyperdefined]

a cleaner version of my previous pull request, no ugly history this time.

adds support for newgrounds video & music.

example links:

• https://www.newgrounds.com/portal/view/938050 - video
• https://www.newgrounds.com/audio/listen/500476 - music

~~videos are returned as the highest quality available. support for picking the resolution could be added easily, since newgrounds stores multiple resolutions.~~

this pull request would close #620 (except for art, but I don't see a reason for it being added here).

[hyperdefined]

PR updated for cobalt 10, also added support for picking quality (if the video has it). If the video doesn't not have the quality selected, it will pick one closer.

[hyperdefined]

Updated again, moved tests to new format.

[hyperdefined]

rebased for cobalt 11