Adds the bar subcommand `gaps <amount>|<horizontal> <vertical>|<top>
<right> <bottom> <left>` to set gaps for swaybar. Due to restrictions on
margins for a layer_surface, only the sides that are anchored to an edge
of the screen can have gaps. Since there is support for per-side outer
gaps for workspaces, those should be able to be used instead for the
last side.
Allows bar-subcommand to be a valid bar-ids
Destroys runtime created bar if trying to use a config only subcommand
Allow subcommands (except for id) to be ids
Brian Ashworth
Connor E
Ryan Dwyer
sghctoma
emersion
Drew DeVault
Zandr Martin