Replace react-redux with the data module in the editor module

[youknowriad]

This PR updates all occurrences of react-redux in the editor module with withSelect and withDispatch from the data module. I notice a gain of 100Kb unminified in the editor module. It's not huge but still a good improvement.

Testing instructions

Check that:

• Post visibility, post sticky, post schedule date, post tags, post categories are updated and saved properly
• Reverting to draft work
• The code editor works
• Leaving with dirty changes trigger a modal
• The writing flow works (arrow navigation)

[gziolo]

🎉

[gziolo]

Travis complains 😱 😄
Another snapshot needs to be regenerated.

[youknowriad]

Stupid snapshots :)

[gziolo]

Looks great, I tested and didn't discover any regression. Awesome work 🥇

We still use redux-multi and redux-optimist. Should we reavelaute their usage?

[gziolo]

So we have this sorted out, too. Awesome 💯

[youknowriad]

We still use redux-multi and redux-optimist. Should we reavelaute their usage?

redux-multi is just small helper allowing array dispatches, it should be fine to remove if we really want to but redux-optimist seems important.