Add example app to Aries Askar for react native

[TimoGlastra]

Because we can not have tests right now for the React Native wrapper, we can add an example app with some buttons to execute the code and make sure it works.

It MUST be an Expo app to keep the repo a lot smaller and should work with the latest version of RN and Expo.

[berendsliedrecht]

Just so I don't forget the requirements of this application I will write them down here.

1. Expo application to reduce repository size
2. (only) be able to use locally-built libraries

• Can do with libraries from Github release as well, but locally-built are preferred.

3. Should include some pages with buttons to mock the tests as is done in Node.JS

Far future:

1. Integrate the application into the CI, Maestro might be a good fit for this, but it is not required.

Feel free to leave suggestions here as well.