Draw shape to create polygon

**Is your feature request related to a problem? Please describe.**
When I'm creating a fine segmentation of a complicated shape, selecting each vertex of a polygon is very time-consuming.

**Describe the solution you'd like**
Click-and-drag around a shape to trace its outline and have an approximated polygon automatically generated from the curve. If this could work using a stylus on a tablet that would be even better.

**Describe alternatives you've considered**
If we had a very accurate and fast grab-cut implementation (or a similar type of tool) that could work as an alternative.

**Additional context**
I've used this method of annotating using [coco annotator](https://github.com/jsbroks/coco-annotator) but I'm interested in using the expanded possibilities of label studio to annotate a wider variety of labels and the ecosystem in general.

Below is an example of how you could use this type of tool to easily annotate a circular object.