remove unnecessary global typescript namespace declaration

[pgoldberg]

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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: https://github.com/react-grid-layout/react-draggable/blob/44a8c6ed103ec6c0a4dda5faf7f8ebca16f9b325/package.json#L24