R1:cc964550f945

Ellipsize long labels in Add Action area to avoid text overlap

Summary:
Add CSS to ellipsize long labels and disable text wrapping

Closes T15707

Test Plan:
Set a long custom "action" label in `/config/edit/maniphest.points/`; go to a Maniphest task; open all items in the "Add Action..." dropdown.

Example config:

```
{
"enabled": true,
"label": "Points",
"action": "Set Points Yeah Points Points Much Points"
}
```

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed…