Add Grandstream Home integration

[wtxu-gs]

This integration adds support for Grandstream GDS/GNS/GSC devices.

Features:

• System status sensors
• Zeroconf discovery

Breaking change

Proposed change

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Add Grandstream Home integration documentation
• Link to brands pull request: Add grandstream brand assets

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

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

• Documentation added/updated for www.home-assistant.io

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

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies a diff between library versions and ideally a link to the changelog/release notes is added to the PR description.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[mawoka-myblock]

The source for the library is missing: https://github.com/GrandstreamEngineering/grandstream_home_api

[wtxu-gs]

The source for the library is missing: https://github.com/GrandstreamEngineering/grandstream_home_api

It is added now

[wtxu-gs]

docs PR: home-assistant/home-assistant.io#44623

[edenhaus]

I did an initial review until I stopped as this PR is to huge. Some code needs to move to the library and also the config flow is huge. Please refactor the code and make it more readable.

Also the library needs a working workflow to deploy directly to pypi.
As 10.000 changes is to much, can we just add a single device/model in this PR and then add other models in a follow up PR. This PR needs to be a lot smaller

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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