Separately configure max size of remote media (from max size of uploaded media)

[Cyberes]

Description:

I have max_upload_size set to 40M. This is great and all, but what if a remote media file is larger than that? Well, Synapse refuses to process it and the file fails to load for the client.

Here's the error the backend returns:

{"errcode":"M_TOO_LARGE","error":"Requested file is too large > 41943040 bytes"}

It feels like Synapse is punishing the user for the arbitrary actions of someone else on another homeserver.

I would like to set the max size for remote media separately from max_upload_size, maybe around 200M. If we ever implement media purging then it would be real easy to delete the file after a certain number of days and re-download it if a user ever requests it in the future.