Setup linters for codebase concistency

[flexbox]

After digging a bit the codebase i noticed:

• Unused style
• inconsistencies in file formatting

Here is what I use on all my projects to detect automatically some mistakes. https://github.com/flexbox/react-native-bootcamp/blob/main/challenges/ecosystem/02.md

first commit is to setup ESLint to avoid having "useless dead code"

second commit adds Prettier and ESLint rules only for React Native

4th one ran the linter on all the codebase

+4,794 -3,253

😅 sorry about this one but we could change some rules now if you don't like it but they are mainly from react-native community

we still have some "error" that we could fix over time

[BenjaminWatts]

Merci!