Switch to Yarn workspaces

[cross19xx]

Summary

Refactoring the codebase to use yarn workspaces. Resolved #493

Installation

[cross19xx]

Steps leading to this change:

• Moved eslint, jest and its dependencies to the project root

• Moved .release-it.json, babel.config.js, dont-cleanup-after-each.js, pure.js, package.json, src and typings into packages/react-native-testing-library

• Due to issues moving flow, I kept flow-typed and .flowconfig at the project root and installed flow-mono-cli. The symlinks are created after post install on the project root

• Fixed docusaurus theme configuration by changing themeConfig.links to themeConfig.items in the docusaurus.config.js

• All libraries that were installed in the project root had their versions changed to "*"

• Switched all examples to use expo to reduce project size since expo did not require the android and ios directory

[thymikee]

I'm not convinced we need flow-mono-cli. I'd like to have a single Flow instance looking over whole project from the root.
Also, the PR needs a rebase

[cross19xx]

I'm not convinced we need flow-mono-cli. I'd like to have a single Flow instance looking over whole project from the root.
Also, the PR needs a rebase

It was more for future cases. In case another package was introduced which had different flow configurations from the global one

[thymikee]

It was more for future cases

Such future may (most likely) never come. There's no reason to add more dependencies to the project "just in case". Only when necessary – e.g. we have long-term plan of supporting such use case. Which we don't.

[thymikee]

linting and type checks should go from the root, please remove and adjust configuration if needed

[thymikee]

FYI, there's no need to differentiate between deps and devDeps in workspace root, I don't mind it though, your call :)

[thymikee]

can we get rid of * in our dev deps and bring back the versions we had in original package.json? I don't mind having * in examples though