Stream media from the remote server to clients while persisting it

...github.com/turt2live/matrix-media-repo/api/r0/download.go

...thub.com/turt2live/matrix-media-repo/api/unstable/info.go

...om/turt2live/matrix-media-repo/api/unstable/local_copy.go

...urt2live/matrix-media-repo/api/webserver/route_handler.go

...po/controllers/download_controller/download_controller.go

...trollers/download_controller/download_resource_handler.go

...a-repo/controllers/upload_controller/upload_controller.go

src/github.com/turt2live/matrix-media-repo/types/media.go

src/github.com/turt2live/matrix-media-repo/util/streams.go

vendor/manifest