Allows multiple Netdata elements per group

[reefab]

Description:

Current Netdata component sensor configuration syntax only allows for one element per group.
This is an issue as this it is often needed to manage two different element at the same time, eg: download and upload for one network interface.

Related issue (if applicable): ref #14897 Called for a PR on that particular issue.

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.io#6296

Example entry for configuration.yaml (if applicable):

Current syntax:

sensor:
  - platform: netdata
    resources:
      snmp_router.bandwidth_eth0:
        element: in
        icon: mdi:download
        name: Download
       snmp_router.bandwidth_eth0:
         element: out
         icon: mdi:upload
         name: Upload

Doesn't work because of the duplicated snmp_router.bandwidth_eth0 key.

New syntax:

sensor:
  - platform: netdata
    host: 192.168.1.89
    resources:    
      Download:
        data_group: snmp_router.bandwidth_eth0
        element: in
        icon: mdi:download
      Upload:
        data_group: snmp_router.bandwidth_eth0
        element: out
        icon: mdi:upload

The previous name option is now mandatory and used as the key. As the name is used as part of the friendly name of the sensor, I'm not 100% sure if this is the right way to do it and I would like confirmation on that point.

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

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

• Documentation added/updated in home-assistant.github.io

[fabaff]

The previous name option is now mandatory and used as the key. As the name is used as part of the friendly name of the sensor, I'm not 100% sure if this is the right way to do it and I would like confirmation on that point.

The template platforms are using an identifier and have an additional friendly_name key. I think that we are fine by using it as a name.

[fabaff]

Breaking change:
The netdata sensor platform now supports multiple values from the same data group. This requires you to update your existing configuration:

sensor:
  - platform: netdata
    host: 192.168.1.89
    resources:    
      Download:
        data_group: snmp_router.bandwidth_eth0
        element: in
        icon: mdi:download
      Upload:
        data_group: snmp_router.bandwidth_eth0
        element: out
        icon: mdi:upload

[fabaff]

Thanks 🐦