Display icons in collapsible action button actions

Problem/Motivation

We start to have more and more actions. Now it's Collapse + Remove + Duplicate.
But there are more to come up.
Readability of the label is getting harder and harder.

We need more than text to identify them.

Proposed resolution

Add icons to each action in the collapsible action button.

In addition to Collapse, Remove, Duplicate, we also should consider library (convert to, detach from) actions.
And whatever else comes up. :-)

Remaining tasks

API changes

Data model changes