copy object encryption fixes

copy object encryption fixes

This contains code to allow copyobject to copy encrypted objects.

It includes additional data paths to communicate data from the
rest layer down to the sal layer to handle decrypting
objects.  The data paths include logic to use filter chains
from get and put that process encryption and compression.
There are several hacks to deal with quirks of the filter chains.
The "get" path has to propgate flushes around the chain,
because a flush isn't guaranteed to propagate through it.
Also the "get" and "put" chains have conflicting uses of the
buffer list logic, so the buffer list has to be copied so that
they don't step on each other's toes.

Fixes: https://tracker.ceph.com/issues/23264
Signed-off-by: Marcus Watts <mwatts@redhat.com>
(cherry picked from commit bcaaf55f4182da0a980c87c1dbd7e1d3c868626c)

Resolves: rhbz#2300284