Media forwards from encrypted rooms

[hifi]

I believe these don't work because they would need to be decrypted and reuploaded.

[bonswouar]

Not 100% related, but now that MSC3916 is coming unauthenticated media will be disabled (see blog post).
As far as I understand another way to share media to IRC will be needed (maybe using an external service?)

EDIT: Actually I guess MEDIAURL could still be used to map the media storage (outside of synapse), but it would mean bypassing the authentication for all synapse media which doesn't sound great

EDIT²: Should be fixed by #290 by adding a proxy for heisenbridge media :)