Convert to monorepo

[baseten]

Depends on: https://github.com/pixijs/pixi-react/pull/363/files
Part of: https://github.com/play-co/react-pixi/issues/10

Changes

• Move existing code into separate packages: pixi-react, pixi-react-legacy, animated
• Add new animated-legacy package since animated is now a small additional lib with pixi-react as a peer dep, so animated-legacy required for pixi-react-legacy
• Split out TYPES to separate package for easier inclusion
• Add eslint and ts configs as packages
• Add nx
• Make eslint work globally as well as per package for husky compatibility
• Until Remove warnings when linting ignored files eslint/eslint#15010 is resolved remove max-warnings 0 from lint-staged command

[baseten]

@Zyie if you're uncertain about setting up the eslint config as a package, I ended up reverting it in the next PR because it was causing more hindrance than help! #366