Allow multiple google_assistant integrations for splitting entities

Currently the google_assistant integration only caters for a single config. However, it would be nice if multiple configurations could be added to allow better control.

To understand what I mean, this is my scenario.

I have a large house that technically has 2 completely separate living areas. Essentially a house with a joined granny flat.
So, this means there are 2 master bedrooms, 2 kitchens… basically 2 of every room.
Now, if I use the standard setup for google_assistant I would have to name all of my rooms XXX Kitchen and YYY Kitchen. If they are both just named Kitchen, Google will turn on/off the lights in both kitchens whenever a command is issued.

If however, multiple google_assistant integrations could be added to the config then, each user would just add the config that is for their part of the home to the Google Home app. This would allow me to just say OK Google, turn on the kitchen light and it would turn on my kitchen light and not my parents kitchen light.

The config would look something like this.

google_assistant:
  projects:
    - project_id: mumAndDad_homeassistant
      service_account: !include mumAndDad_service_account.json
      report_state: true
      secure_devices_pin: !secret secure_device_pin
      expose_by_default: false
      entity_config: !include google_assistant/mum_and_dad.yaml
    - project_id: meAndWife_homeassistant
      service_account: !include meAndWife_service_account.json
      report_state: true
      secure_devices_pin: !secret secure_device_pin
      expose_by_default: false
      entity_config: !include google_assistant/me_and_wife.yaml