DrawTool: expose callbacks when a shape being edited has changed

ℹ️ Funded by an industrial customer.

When using the edition mode of DrawTool, there is currently no way to be notified when the user has effectively changed the shape (e.g by moving a point, or inserting a point...).

Add callbacks to the DrawTool

In addition to the onBeforePointRemoved, onBeforePointMoved and onSegmentClicked, we should expose symmetrical callbacks after the update has been done:

• onPointRemoved
• onPointMoved
• onPointInserted

along with a more general onShapeUpdated callback that will be trigger when any of those events occur.

Each callback should contain the relevant shape that has changed, as well as the relevant point index, if applicable (i.e point removed).

Add events to the Shape entity.

In addition to adding callbacks to the DrawTool, we can also add events on the Shape entity itself, whenever its geometry has changed (i.e the .points array has been updated).