Remove support for deprecated Sonos configuration

[amelchio]

Breaking Change:

Configuring the Sonos integration as a media_player: platform in configuration.yaml was deprecated in 0.72 and has now been removed.

Description:

This cleans up the Sonos setup:

• Remove setup_platform support
• Remove discovery_info support that is never used because we now just prompt to set up a config entry
• Move config schema to the component (so the config is actually validated)
• Use cv.ensure_list_csv to split hosts

I did not want to update all the old tests that depended on the deprecated config so I started over with fixtures (which I don't know much about, so I kept it small for now).

Example entry for configuration.yaml (if applicable):

sonos:
  media_player:
    hosts:
      - 192.0.2.25
      - 192.0.2.26

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox.
• There is no commented out code in this PR.