This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.
Removes the recycle operation and adds an operation
to cancel any badged sends on and endpoint. Calling
Revoke + CancelBadgedSend is equivalent to Recycle
on a badged endpoint
