limel-action-bar: support condtional disabling of action-bar-items

[paulinewahle]

New feature motivation

Marketing in CRM uses the promoted actions bar (limec-contextual-action-bar) for email sending actions. The send action can only be triggered when recipients and content have been added and should be disabled until then. The only current option to conditionally hide the action makes for poor UX because the user is expecting to find a send action and by hiding the action, the user doesn't receive contextual clues why the action isn't available.

New feature description

Part 1: Disabled state
Limel-action-bar-item already supports disabled state, the same state should get support in the floating action bar.

Part 2: Disabled feedback
Any unavailable action is there to point to its cause. The tooltip already in place for enabled chips can hold the reason for the disabled state.
Touch-screen affordance: This is covered by the existing behavior of the tooltip rendering on tap for both enabled and disabled action buttons.

[Kiarokh]

@eketorp and I have been talking about enabling this "conditional rules" for not only "Visibility" but also for "Disability" or "Readonly-bility" of stuff here and there. Today we have a similar approach for "Reducing presence" or info-tiles for example. So technically it's not hard to do so, when we're done with the visibility work.

However, you're asking also for a custom tooltip that explains why the button is disabled. We don't have such a things right now, for promoted actions. We could add that too. So just mentioning it to explain that there are two things you need to support your intended design.

However, the quickest way is to use the current "Visibility" settings to have two different "Enabled" Send buttons:

1. Is shown when no recipients are added, and when clicked, it shows a modal that explains things, or navigates to the recipients tab, or opens the "add recipients flow" or something along those lines.
2. Is shown when there are recipients, and takes the user through the send ing flow...

I don't know which one is better for your case, but even if we had the disabled feature, I'd still lean towards this other more informative and interactive design i think

[paulinewahle]

With other things left to do before the release we will wait with spending time on workarounds until we know we won't get the disabled option in time, ping @hannahu