Authenticated media / MSC3916 support.

[Half-Shot]

Media across matrix is slowly starting to require authentication, with the major servers out there now requiring new media to be accessed with a bearer token. Widgets obviously do not have access to the client's access token, so will be unable to access this media.

I suspect a good solution here would be to provide APIs for download / thumbnail APIs, and pass along a buffer with the media.

[Half-Shot]

Oh, I actually missed that MSC4039 exists so there is a download API. No thumbnail though 😞