[Merged by Bors] - Feature/epaint

[zicklag]

Add epaint plugin for simple shape rendering that can be useful while creating custom debug rendering for games.

[zicklag]

bors r+

[bors[bot]]

Pull request successfully merged into master.

Build succeeded:

• build-and-test-native (macos-latest, stable)
• build-and-test-native (ubuntu-latest, stable)
• build-and-test-native (windows-latest, stable)
• build-wasm
• check