Use chokidar 3.x directly

[jeffposnick]

R: @tropicadri

Fixes #2912

This uses the latest chokidar 3.x directly, instead of relying on the glob-watcher wrapper which used chokidar 2.x under the hood. This resolves some compatibility issues with chokidar 2.x.

In the course of making these changes, I also realized that workbox-cli wasn't properly reading the new workbox-build TypeScript definitions, as it had an override module in place. This PR removes that override module and takes better advantage of the new types internally.

Since workbox-cli is run as a transpiled binary and not intended to be loaded as a module by third-party code, I think that swapping out the internal type definitions should be considered a non-breaking change.