Port front-end part of 9660aa4543deff41c60d131e081137f84e771499 to glitch-soc [API] This makes use of a new media posting API (/api/v2/media), supporting background processing of uploaded files. For Pleroma's purposes, this could be handled the same as /api/v1/media since afaik Pleroma doesn't do any transcoding. Signed-off-by: Thibaut Girka <thib@sitedethib.com>