fix(gantt): tasks resizing indicators should point both left and right

[TeyaVes]

closes: #5251

The resize handle- k-resize-e and k-resize-w classes are used for positioning the resizing indicators (k-resize-e is with left:0, k-resize-w is with right:0). This is why, we cannot update the classes to k-resize-ew or if we update them, we'll need to add a new class used for positioning. Thus, in order to keep the same rendering, I've set the cursor: ew-resize to the .k-resize-handle selector.