Example of the new network inspector

[byCedric]

Description

Opening a PR to opt-in to the new debugger and network inspector (because @frankcalise asked how you could set it up). Feel free to close this PR any time, just wanted to give it to Frank.

Trello Card

• Bumped expo to 48.0.16
• Added EXPO_USE_CUSTOM_INSPECTOR_PROXY=true when running yarn start
• Added unstable_networkInspector to the expo-build-properties plugin

You can use run:ios or run:android to build the updated expo-dev-client. (but you have to start the bundler with yarn start)

Graphics

Checklist:

• I have done a thorough self-review of my code
• I have tested with a screen reader and font-scaling turned on and added necessary accessibility features
• I have run tests and linter

[mazenchami]

@byCedric thanks for opening this PR. We really appreciate the contribution. I'll discuss this further with Frank!