Add diagnostics to KNX

[farmio]

Proposed change

Add diagnostics to KNX

An example of the output would be:

{
    "home_assistant": {
        "installation_type": "Home Assistant Core",
        "version": "2022.2.0.dev0",
        "dev": true,
        "hassio": false,
        "virtualenv": true,
        "python_version": "3.9.7",
        "docker": false,
        "arch": "arm64",
        "timezone": "UTC",
        "os_name": "Darwin",
        "os_version": "12.1",
        "user": "farmio"
    },
    "xknx": {
        "version": "0.18.16.dev",
        "current_address": "1.0.255"
    },
    "config_entry_data": {
        "state_updater": true,
        "rate_limit": 20,
        "individual_address": "15.15.250",
        "multicast_group": "224.0.23.12",
        "multicast_port": 3671,
        "connection_type": "tunneling",
        "local_ip": null,
        "host": "10.1.0.40",
        "port": 3671,
        "route_back": false
    },
    "configuration_yaml": {
        "light": [
            {
                "name": "K\u00fcche Esstisch",
                "address": "1/1/45",
                "state_address": "1/0/45"
            }
        ]
    },
    "configuration_error": null
}

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)
• 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:

Checklist

• 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
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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 link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

To help with the load of incoming pull requests:

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

[probot-home-assistant]

Hey there @Julius2342, @marvin-w, mind taking a look at this pull request as it has been labeled with an integration (knx) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[balloob]

ok to merge after adding a test or exclude file coverage

[marvin-w]

Works fine locally!

[mib1185]

Please address these comments i a new PR

[mib1185]

hass system info is added central with #64670, so it can be removed here.