Rewrite code in TypeScript

[mdingena]

Context

PR #8 introduced some type definitions, but because this package relies on @envato/react-resize-observer-hook with missing type definitions, there were types missing for some of the things that this package exposes (like <Provider> and useResizeObserver()).

Types were introduced in envato/react-resize-observer-hook#3 to address that.

This PR updates the codebase to be written in TypeScript, rather than JavaScript with a type definition file. Some other optimisations, API changes, and documentation updates have been added.

Changes

• Rewritten code in TypeScript.
• API changes (non-breaking):
  • <Observe> now supports render functions through children (in addition to using the render prop), giving you the option to use your preferred syntax.
  • useBreakpoints() now also supports object destructuring:
    const { widthMatch, heightMatch } = useBreakpoints(options);
• Resolves Provider declaration missing in index.d.ts #11.