Convert Preferences into a function component

[lindapaiste]

Progress on issue #824

Continue breaking up PR #2054 into more manageable pieces. Here I am converting Preferences from a class component to a function component while keeping all the logic the same. I'm not including the improvements to the font size input which were causing tests to fail. I will submit those separately.

Should be merged after #2329

Changes:

• Preferences
  • Convert to a function component.
  • Use Redux hooks useSelector and useDispatch instead of connect HOC.
  • Use useTranslate hook instead of withTranslation HOC.
  • Use a useRef hook instead of property this.fontSizeInput.
  • Use a useState hook for the fontSize state. I tried to keep this as similar to before as possible so I made the state be an object even though this is silly.
• Preferences.unit.test.jsx
  • The component has no more props.
  • Helper function subject now takes the initial state as an argument.
    • Remove all beforeAll effects, which were used to set props.
    • Call subject with the relevant initial state for each test, ie. subject({ lintWarning: false }).
  • Remove mocks of functions setLintWarning etc. and spy on on the action creator instead.
    • I'm calling this object of spied-on action creators props so that tests like expect(props.setFontSize).toHaveBeenCalledTimes(1); will work the same as before, even though it's not actually a prop.
  • No changes to any expect conditions as there is no change to behavior.
• IDEView
  • Remove all props passed to <Preferences/>.
  • Remove unused or unecessary propTypes.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123