* Use buildcache for iOS builds
from https://github.com/mikehardy/buildcache-action
* Update build-ios.yml
* Update build-ios.yml
* Specify compiler options to make buildcache work
* Update build-ios.yml
* Adds a "Build Android App" action that builds example/android (I think we can also just build android/, but this is just double safety)
* Adds a "Build iOS App" action that builds example/ios (disabled for now as that is very expensive)