[In Progress] Feature: Create Circle

[seveibar]

Created from #17, this PR creates a new tool "create-circle". Remaining issues:

• When the create circle tool is selected, clicking the little button to open the classification dialog should not create a new circle
• The circle tool icon should be a dotted circle
• (optional) xr and yr should be locked to the image ratio such that the circle isn't an ellipsis

Note: Prettier should be run on any changed files, I installed the prettier extension to my IDE and set it to configure on save to make this easier

[saichander17]

@seveibar, Will you be introducing ih and iw in the reducer's state variable?
If not how will you set the x-radius and y-radius properly in the region.

[saichander17]

@seveibar , May I know if you're going to work on this in near future?