Before this change when the context was cancelled (due to
--max-duration for example) this could deadlock when uploading
multipart uploads.
This change fixes the problem by introducing another go routine to
monitor the context and close the pipe with an error when the context
errors.
This adds expire and unlink fields to the PublicLink interface.
This fixes up the affected backends and removes unlink parameters
where they are present.
- Change rclone/fs interfaces to accept context.Context
- Update interface implementations to use context.Context
- Change top level usage to propagate context to lover level functions
Context propagation is needed for stopping transfers and passing other
request-scoped values.
