Update service domain for onvif from 'camera' to 'onvif'

[raman325]

Breaking Change:

This change breaks existing service call references to the camera.onvif_ptz by changing the service call to onvif.ptz. My understanding is that because this is not a service provided by the base camera component, it should live in the domain of the onvif component instead. If that's the case, then it also makes sense to update the service name.

Description:

Update the domain and service name for camera.onvif_ptz. See this comment for context: #28890 (comment)

Related issue (if applicable): Related to #27289

Pull request with documentation for home-assistant.io (if applicable): home-assistant/home-assistant.io#11294

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly. Update and include derived files by running python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

[balloob]

This is being done in #29069, which is also introducing a new service.