Implement auto linking

[kmelmon]

Proposal: Add support for auto-linking native modules. Also consider implementing react-native link (lower priority)

Summary

With version 60, react-native now supports auto-linking. This item is tracking making sure RNW supports it as well. See https://facebook.github.io/react-native/blog/2019/07/03/version-60

In addition we can consider implementing the Linking native module. See: https://facebook.github.io/react-native/docs/linking
We'll use this issue to decide whether or not we actually do this work as it might be unnecessary.

Motivation

Basic example

Open Questions

[ahimberg]

We do have https://github.com/microsoft/react-native-windows/blob/master/vnext/ReactUWP/Modules/LinkingManagerModule.cpp which partially implements the Linking module.

A couple notes:

1. openURL doesn't have all the args we'd probably expect on a windows machine. specifically there is no arg to control if this is an external url where a safety prompt should be included. We for now do not include the prompt.
2. we're missing initialurl and opensettings. In our app we looked at doing this but have multiple activation scenarios that the ios/android impl didn't seem to handle so added our own protocol activation events instead

[chrisglein]

@kmelmon Is this the same as this? Don't want to track in duplicate.

[kmelmon]

@chrisglein I'm 90% sure these are separate features. #2132 involves changes to the CLI which control how your build pulls in other modules at build time, whereas the linking module happens at runtime.

[ahimberg]

Yes they're totally different things

[acoates-ms]

Added the triage tag back, it sounds like the expo guys would like this module to work, as they use it to open user projects. -- So maybe that would bump the priority up some.