Remove import CSS in dev-tools and fix typos

[hd4ng]

• I think you will not need dev-tools.css anymore since you're using emotion already
  

  bookshelf/src/dev-tools/dev-tools.js

  Line 9 in 41ea6f3

  import './dev-tools.css'

• Typos: enableDevToos => 'enableDevTools'
  

  bookshelf/src/dev-tools/dev-tools.js

  Line 160 in 41ea6f3

  const [enableDevToos, setEnableDevToos] = useLocalStorageState(

[kentcdodds]

Thanks!