Allow actions to be hidden in the index view

[calebuharrison]

I'd like to prevent some actions from showing up in the index view, only allowing them to appear in the show view. This could be as simple as an option set on the action class.

[calebuharrison]

Actually, now that I think about it - I'd like for this to use policies somehow. I can definitely see it being useful to give certain roles of users access to certain actions.

[calebuharrison]

Alternatively, maybe the action DSL could accept the visible option like other fields. You could also use hide_on or only_on.

[adrianthedev]

Yeah, that's what I was thinking of. Have a visible lambda that receives the view (and some other data) and you could toggle the visibility through that lambda.

[adrianthedev]

@nulldotpro can you have a look at this PR? Would this cut it?

This is how you would use it.

[calebuharrison]

@adrianthedev Left a comment for you. Looking good, thanks so much for making this happen!