tests: t3310-flags: check all gpt boolean flags, too

tests: t3310-flags: check all gpt boolean flags, too

* tests/t3310-flags.sh: Check gpt as well as msdos flags.
Parametrize mkpart usage.
Accommodate gpt-induced difference in parted's print output
GPT partitions have a name, while msdos ones do not.
This also fixes the "on_and_off" perl flag extraction regexp,
which before was using $1 with no corresponding () group.