Add a loop to check that each test covers all of the pg_dump runs.  We
(I) had been a bit sloppy when adding new runs and not making sure to
mark if they should be under like or unlike for each test, this loop
makes sure that the test system will complain if any are forgotten in
the future.

The loop also correctly handles the 'catch all' cases, which are used to
avoid running unnecessary specific checks when a single catch-all can be
done (eg: a no-acl run should not have any GRANT commands).

Also, re-enable the testing of blobs, but use lo_from_bytea() instead of
trying to be cute and writing out to a file and then reading it back in
with psql, which proved to be difficult for some buildfarm members.
This allows us to add support for testing the --no-blobs option which
will be getting added shortly, provided the buildfarm doesn't blow up on
this.