packagefeed-ni-core: Add packagegroup-ni-graphical
packagefeed-ni-core: Add packagegroup-ni-graphical

Replace packagegroup-ni-xfce with the newly created, all encompassing
graphical packagegroup.
Since we support only a single distro that has x11 always enabled,
remove conditionals for graphical packages and always include them.

Signed-off-by: Shruthi Ravichandran <db26f49c821f5e8eba3f4f30a1d200e2416b0696@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt