[jnigen] Add ability to use source dependencies from Gradle (https://github.com/dart-lang/jnigen/issues/231)

* Add google maven repository to maven
* add_gradle_sources option
* Add proguard rules and EmojiConfig usage in example
11 files changed
tree: ad0e98496ccc59e029278c7b49a163725e064e18
  1. .github/
  2. pkgs/