Clicking a link handle disables linking

[ebaratte]

On each chart item, link handles (blue dots) can be dragged from to create links between different items.

The specific issue arises when clicking (instead of dragging from) a link handle: the handle itself, as well as all other handles are permanently disabled. One needs to fully reload the chart to make it work again.

After a bit of investigation, I believe that the issue lies in https://github.com/worktile/ngx-gantt/blob/2373719e639708c192d08d6c3a22fdc288e59cc3/packages/gantt/src/components/bar/bar-drag.ts#L285 : clicking the handle emits the beforeStarted event, but no other events are emitted when releasing the mouse button (in particular the ended event)