adding support for openwakeword as a wake word engine

[bmcwilliams96]

Adds a toggle in the home assistant integration section to switch between micro and openwakeword

[pacmac]

Seems this has passed the checks but has not been approved yet ?

Is there any way of using this pull request instead of the main branch / release ?

I tried this but does not appear to work:

external_components:
  - source:
      type: git
      url: https://github.com/esphome/home-assistant-voice-pe
      ref: pull/473/head

packages:
  voice_pe: github://esphome/home-assistant-voice-pe/home-assistant-voice.yaml?ref=pull/473/head