block/backup: set copy_range and compress after filter insertion

block/backup: set copy_range and compress after filter insertion

We are going to publish copy-before-write filter, so it would be
initialized through options. Still we don't want to publish compress
and copy-range options, as

1. Modern way to enable compression is to use compress filter.

2. For copy-range it's unclean how to make proper interface:
 - it's has experimental prefix for backup job anyway
 - the whole BackupPerf structure doesn't make sense for the filter
 So, let's just add copy-range possibility to the filter later if
 needed.

Still, we are going to continue support for compression and
experimental copy-range in backup job. So, set these options after
filter creation.

Note, that we can drop "compress" argument of bdrv_cbw_append() now, as
well as "perf". The only reason not doing so is that now, when I
prepare this patch the big series around it is already reviewed and I
want to avoid extra rebase conflicts to simplify review of the
following version.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824083856.17408-9-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>