[core] fix(useHotkeys): remove synthetic default import of React

[styu]

Fixes #0000

Checklist

• Includes tests
• Update documentation

Changes proposed in this pull request:

Revert to using import * as React syntax for useHotkeys, else you get these errors when allowSyntheticDefaultImports is not enabled:

[error] TypeScript error node_modules/.pnpm/@blueprintjs/core@3.41.0_react-dom@16.14.0+react@16.14.0/node_modules/@blueprintjs/core/lib/esm/hooks/hotkeys/useHotkeys.d.ts:1:8 - error TS1259: Module '"/home/git/project/node_modules/.pnpm/@types/react@16.9.55/node_modules/@types/react/index"' can only be default-imported using the 'allowSyntheticDefaultImports' flag
1 import React from "react";
         ~~~~~
  node_modules/.pnpm/@types/react@16.9.55/node_modules/@types/react/index.d.ts:65:1
    65 export = React;
       ~~~~~~~~~~~~~~~
    This module is declared with using 'export =', and can only be used with a default import when using the 'allowSyntheticDefaultImports' flag.

Reviewers should focus on:

Screenshot

[blueprint-bot]

Revert es module style import for React in useHotkeys

Previews: documentation | landing | table