* Add SVG string generator for radial gradients
* Add the UI for the linear vs radial radio inputs
* Initial radial gradient support for gradient tool
* Enabled click and drag support for radial gradients
* Refactor code for gradient in properties panel
* Added gradient type to gradient struct
* Finish refactor to use gradient_type instead of fill
* Fix lint issue
* Combine LinearGradient and RadialGradient in Fill enum
* Add label to properties panel and fix bug
Co-authored-by: Robert Nadal <Robnadal44@gmail.com>
Co-authored-by: Oliver Davies <oliver@psyfer.io>