Enhance voice configuration

Enhance voice configuration

Various tweaks to the new voice configuration support:
- Moved "Version" choice on the main menu back down to the last
  choice, since it's less likely to be used.
- Pull in qt-qrcode library's quickitem support and use it to
  display a QR code when Alexa authorization is required.
- Reworked layout of voice configuration dialog to tighten up
  spacing and make more room for the QR code.
- Tweaked voice configuration dialog logic to only show the login
  prompting when in not-authorized state. Ideally, a deauth button
  would be shown in the authorized state, but the voiceagent API
  currently does not enable that AFAICT.
- Replace voiceagent ID with vendor in voiceagent configuration
  dialog, as the ID is more of an internal thing that's not useful
  to users.
- Tweaked some text colors in voiceagent configuration dialog for
  better consistency with the other settings pages.
- Switched voiceagent configuration dialog positioning to center
  it on-screen, as that seems more consistent with the look of
  the other settings pages.
- Made the previous two changes to the wired settings configuration
  dialog as well for consistency.
- Updated the voice settings icon with a microphone icon to match
  the default icon shown for the homescreen PTT button.
- Updated the wired settings icon with a more typical network icon
  to avoid confusion.

Bug-AGL: SPEC-2981

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I75560e3cab393e6efdfb1310f266e5b6bb0534d6