Migrate @storybook/addon-knobs to typescript

[emilio-martinez]

Issue: #5030

What I did

Migrate @storybook/addon-knobs to typescript.

**Note: ** To make this easier to review, I did an initial commit with a straight file rename from js => ts, and subsequent commits will add the types accordingly.

How to test

If all works correctly, functionally nothing should change to lib consumers beyond getting a typed package.

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[gaetanmaisse]

@emilio-martinez to answer your question #5030 (comment), you can add @types/react-color in addon-knobs package, just run yarn add -D @types/react-color in storybook/addons/knobs folder

[gaetanmaisse]

Great job @emilio-martinez ! Just a few comments you can simply resolve in a new commit 😉

[emilio-martinez]

@gaetanmaisse feedback addressed. FYI, I rebased to resolve a merge conflict.

DeepScan is calling out REACT_MISUSED_UPDATE_IN_SET_STATE, but I'd prefer to tackle in a separate PR once this is merged, if that's okay.

[sami616]

Hi. I've just upgraded to SB 5.2 and my build is failing due to a TS error in addon-knobs. Something about react-color missing?

[shilman]

@sami616 Can you file an issue and include the details? We'll try to get you fixed up.