Implement add meeting point flow

Implement the add meeting point flow in onboarding.

This flow is very similar to the one for addresses. Please reuse as much as possible from https://github.com/code4romania/de-urgenta-android/issues/13

The addresses should also be stored locally after the success response from the backend.

In case there is no internet connection when the user tries to save the address, an error should be displayed ( depends on https://github.com/code4romania/de-urgenta-android/issues/8 )

Please define related colors and text & button styles in the corresponding values files.

Some basic scaffolding was added, but it needs to be cleaned up.

Map provider: here maps
to be added: save meeting point endpoint


[Link to design in Figma](https://www.figma.com/file/d6n3MPVRWbL5jP2NmvW96b/De_Urgenta?node-id=1466%3A530)