Support for adding polygon holes

[offtherailz]

Description

Actually we can edit polygons and multipolygons that has holes. Anyway, there is no way to insert an hole in an existing geometry. We should provide in DrawSupport the possibility to insert the hole. MapStore may in the future provide the necessary drawing tools to enable this functionality in its own UI

Acceptance criteria

• [ ] DrawSupport should allow to have a mode for inserting an hole in a geometry.
• [ ] Support for OpenLayers only at the moment.
• [ ] Unit tests will demonstrate the functionality is working (and how it woks)
• [ ] Document the additional options in DrawSupport JSDOC

Other useful information

[offtherailz]

This is not testable on UI yet.

[offtherailz]

moved in next release. Not mandatory for this one