arrows: separate out handle behavior from labels (#2621)

This is a followup on the arrows work.
- allow labels to go to the ends if no arrowhead is present
- avoid using / overloading TLHandle and use a new PointingLabel state
to specifically address label movement
- removes the feature flag to launch this feature!

### Change Type

- [x] `patch` — Bug fix

### Release Notes

- Arrow labels: provide more polish on label placement

---------

Co-authored-by: Steve Ruiz <steveruizok@gmail.com>

packages/editor/src/lib/components/default-components/DefaultHandle.tsx

@@ -14,14 +14,6 @@ export type TLHandleComponent = ComponentType<{
 
 /** @public */
 export const DefaultHandle: TLHandleComponent = ({ handle, isCoarse, className, zoom }) => {
-	if (handle.type === 'text-adjust') {
-		return (
-			<g className={classNames('tl-handle', 'tl-handle__text-adjust', className)}>
-				<rect rx={4} ry={4} width={handle.w} height={handle.h} />
-			</g>
-		)
-	}
-
 	const bgRadius = (isCoarse ? COARSE_HANDLE_RADIUS : HANDLE_RADIUS) / zoom
 	const fgRadius = (handle.type === 'create' && isCoarse ? 3 : 4) / zoom