samba-tool visualise: expand set of --color switches

samba-tool visualise: expand set of --color switches

To match convention, and elsewhere.

We can't easily use colour.is_colour_wanted() because we could (via
--output) be intending to write to a file that isn't open yet, so we
have no .isatty() to query.

Also, because --color-scheme implies --color (as documented in
--help), it trumps most 'auto' checks, but not NO_COLOR.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>