build-with-container: improve source rpm detection

build-with-container: improve source rpm detection

Improve source rpm detection by adding a new detection method that
executes and rpm command in a container to get exactly the version of
the source rpm that the ceph.spec file would have generated.  For
backwards compatibility and that I don't entirely trust myself to have
tested this the old methods are still available.

The old `--rpm-no-match-sha` is now an alias for `--srpm-match=any` to
cause it to build any (unique) ceph srpm it finds.
`--srpm-match=versionglob` retains the previous default behavior of
using a glob matching on the git id or ceph version value.  The new
default of `--srpm-match=auto` implements the rpm command based behavior
described above.

All of this is wrapped in a new step `find-rpm` but that's mostly an
implementation detail and for testing.

Signed-off-by: John Mulligan <jmulligan@redhat.com>