[PLAT-4932] feat(react-native-cli): Add install command

[bengourley]

Adds bugsnag-react-native-cli install command.

Unit tests included for relevant parts. Interactive CLI aspects will be test via maze runner at a later point.

To test this out, use the following steps:

• git fetch && git checkout feature/rn-cli-install-cmd
• npm i
• npm run bootstrap
• npm run build
• cd packages/react-native-cli
• npm link (this symlinks the local cli package to your global npm modules)

On a React Native project:

• check that the command is linked up correctly bugsnag-react-native-cli --help
• run bugsnag-react-native-cli install
• verify that Bugsnag is installed (note that it will be integrated in another command insert so won't actually do anything until then)

[bugsnagbot]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	40.57 kB	12.52 kB
After	40.57 kB	12.52 kB
±	No change	No change

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