Chore: Migrate App/index.tsx to hooks

[reinaldonetof]

Proposed changes

Migrate the App/index.tsx to hooks.

This is the second file, after the index.js. Here we start with a lot of providers, the redux and some modals.

Issue(s)

How to test or reproduce

• Test the themes, change them to another, and back
• Test the deeplink
• Test when dimension changes
• Test the tablet
• Test the theme in share extension

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

Jira: NATIVE-45

[guilhermedfs]

LGTM!

[liversonp]

Hello. I was reviewing about hooks in react native and I found this way to hook consts using usereducer, I think this can help in clean code

• https://pt-br.reactjs.org/docs/hooks-reference.html#usereducer

[diegolmello]

Why?

[reinaldonetof]

https://github.com/RocketChat/Rocket.Chat.ReactNative/pull/4401/files#diff-b788f0c6b6e92a2a43dedd61dd4e596b4b0f981e30bcfd88e2f5d30b2de3a7dbR39

Because I changed the function newThemeState to receive only the property required, not the state completely.

[dnlsilva]

Add a comment to your task saying that it has to be well tested.
All app works.
Open and close, push etc.