Add connection control for netgear_lte

[amelchio]

Description:

This adds two Netgear LTE services, a feature requested in the forum.

Also makes the host argument optional for the existing service in the common situation where only one device is configured.

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#9179

Checklist:

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

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 (example).
• New dependencies have been added to requirements in the manifest (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

[MartinHjelmare]

Looks good!

[MartinHjelmare]

A service call is when the service is called. We're adding two new services here, I'd say.

[amelchio]

Thanks, I updated the description.