Drop SVGKit and support iOS 13+ native SVG rendering
Important
For current SVGKit user, we move the SVGKit support into another repo: https://github.com/SDWebImage/SDWebImageSVGKitPlugin
The 1.0.0 version now support iOS 13+/macOS 10.15+, to use the system framework for SVG rendering
The 1.0.0 version also bring the SwiftPM and watchOS support