This commit adds a new tab to the Settings modal: Debugging
This new tab has the append component stacks feature and a new one: break on warn
This new feature adds a debugger statement into the console override
* import * as React from "react";
This is the correct way to import React from an ES module since the ES
module will not have a default export. Only named exports.
* import * as ReactDOM from "react-dom"
Update various parts of DevTools to account for the fact that the global "hook" might be undefined if DevTools didn't inject it (due to the page's `contentType`) it (due to the page's `contentType`)
