remove unnecessary global typescript namespace declaration

[pgoldberg]

Declaring a global module with declare module 'react-draggable' is unnecessary, and can cause type pollution if multiple versions of react-draggable end up in a package.

This is exemplified in this repro: https://github.com/pgoldberg/react-draggable-typings-bug

The global module declaration is not necessary. Typescript will appropriately associate the typings with the react-draggable module, since the typings are declared in the package.json here:

react-draggable/package.json

Line 24 in 44a8c6e

"typings": "./typings/index.d.ts",