User React Native to build a demo to integrate the web map core

We need to test the integration of the core with native app (via webview)
Need to test:
* Display the web map
* Test the touch interaction( tap the tree icon to display a dialog)

Question:
* where should we put the demo to, this repo (core) or a separate one?

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Some hints:

- Please read our [readme](https://github.com/Greenstand/treetracker-web-map-core#treetracker-web-map-core) for more information/guide/tutorial.
- Here is [an engineering book](https://greenstand.gitbook.io/engineering/) in Greenstand.
- To know more about our organization, visit our [website](https://greenstand.org).
- If you want to join the slack community (some resources need the community member's permission), please leave your email address.

Start with the repository README and the linked Greenstand engineering book to understand the web map core and integration guidance. Define where the React Native demo belongs, then test displaying the web map in a native app via webview and tapping the tree icon to display a dialog. Done means the demo location is decided and both interactions work.

Written by the indexing model from the issue text.