Use voluptuous for Proximity

[fabaff]

Description:
Migration of the configuration check to voluptuous. The configuration style was aligned with other components,

Related issue (if applicable): fixes 127528299

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#1205

Example entry for configuration.yaml (if applicable):

proximity:
  home:
    ignored_zones:
      - twork
      - elschool
    devices:
      - device_tracker.nwaring_nickmobile
      - device_tracker.eleanorsiphone
      - device_tracker.tsiphone
    tolerance: 50
    unit_of_measurement: mi
  home3:
    devices:
      - device_tracker.tsiphone
    tolerance: 50
  work:
    devices:
      - device_tracker.elanorsiphone
    tolerance: 10

Would be nice if somebody could take a look at the changes and run a quick test. Thanks.

[balloob]

Tests have to be updated to use bootstrap.setup_component to trigger the schema validation.

[balloob]

Looks like some test broke.

[fabaff]

This became a breaking change.

[happyleavesaoc]

Confirming that this change works, FWIW.