Cookies are handled by cookiejar in memory with fshttp module through
the entire session.
One useful scenario is, with HTTP storage system where index server
adds authentication cookie while redirecting to CDN for actual files.
Also, it can be helpful to reuse fshttp in other storage systems
requiring cookie.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
