This PR adds a polyline hide operator for sculpt mode as well as the
necessary generic callback code to allow using this gesture in other
selection tools.
Added features include:
* *Polyline Hide* operator
* `WM_gesture_polyline_*` callback functions for other operators
* Status bar text while using the polyline modal
* Common *Gesture Polyline* keymap for usage with the modal
Unlike the *Box Hide* and *Lasso Hide* operators, the *Polyline Hide*
operator does not provide a simple shortcut to click and show all
hidden elements in a mesh. This is because the existing operators
operate on a click-drag action while the new operator is invoked by
just a click.
Design Task: #119353
Pull Request: https://projects.blender.org/blender/blender/pulls/119483
55fc1066ac