build: Allow alphanumeric test name suffixes

build: Allow alphanumeric test name suffixes

To allow test names to be more descriptive, allow a suffix to be
added to the numeric name of the test.  e.g. a test can be named
"tests/generic/001-some-descriptive-name".

Name suffixes are limited to alphanumeric characters and dash - the
name is always prefixed with an unique id for easy identification
of a specific test. Hence we can still use shorthand forms such as
"generic/001" when referring to a test and be clearly understood.

Signed-off-by: Jan Tulak <jtulak@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>