rgw/kms/vault - s3tests for both old and new test logic.

rgw/kms/vault - s3tests for both old and new test logic.

Test both "old" and "new" transit logic with s3tests.  Does not test
migration - that will need to be done separately.  I've added
a "flavor" parameter so the test logic can tell the difference
between the "old" engine and the "new" engine.  The vault
keys creation logic now has options to determine whether
the keys created are exportable (needed for the old transit
engine), or not (should be the case going forward with the
new transit engine.)

Fixes: http://tracker.ceph.com/issues/48746
Signed-off-by: Marcus Watts <mwatts@redhat.com>