feat(ts): export the error codes as an enum

fix: ignore the vendor dir to avoid licensing issues

fix: add the `validator` as dependency to onDropCb

This PR:

- Adds validator prop to dependency array as unexpected behavior happens if onDropCb is not using last updated validator function.

Co-authored-by: Roland Groza <[email protected]>

fix(typings): use generics for `getRootProps` and `getInputProps`

fix: Check drag event contains files before showing "copy" cursor

closes react-dropzone#1042

fix: allow validator to be null

feat: add {validator} for custom validation

fix: add supported browsers via browserslist config and close react-d…

…ropzone#630

fix: update internal state when maxFiles prop changes and close react…

…-dropzone#1025

fix: set isDragReject true when maxFiles rejects (react-dropzone#1020)