This command takes a mode, modifiers, button/event name, and pointer
action as arguments. It stores these in the config data structure.
The currently available pointer actions are move-view and resize-view,
which replace the previously hard-coded functionality.
Closing the hovered view with middle click has temorarily been removed
until it is decided if we wish to make this another special pointer
action or perhaps allow running any arbitrary command (which would of
course include close).
`riverctl set-option view_padding 10` becomes `riverctl view-padding 10`
Having set-option doesn't really gain us anything and is more verbose as
well as being slightly inaccurate as the changes instantly apply.
This is trivial to support and allows basic customization without
running a layer-shell program such as swaybg. This is especially useful
in low memory situations.
