cropper-viewer option to behave like like css background-size: cover

[ronnievdc]

Is your feature request related to a problem? Please describe.
I like to use Cropper to show previews of the cropped image as they would appear in an environment where the final image is displayed with the following css background-size: cover; background-position: center center;

Describe the solution you'd like
Extend the cropper-viewer -> resize property with "cover" and "contain"
Add a second property position where center center or other background-position values can be filled

Describe alternatives you've considered
Call CropperSelection.$toCanvas each change (debounced) and create a canvas with object-fit: cover

Additional context