Adds basic icon support for the wireplumber module.
This can be achieved by using `{icon}` in the `format` config and
pairing it with the `format-icons` config as well.
Example:
```
"wireplumber": {
"format": "{volume}% {icon}",
"format-icons": ["", "", ""]
}
```
Adds basic support for showing volume via wireplumber. Allows specifying
the node-id or falling back to the default Audio/Sink node id if node-id
is not set. If tooltip on hover is enabled, will show `{node_name}` by
default otherwise `tooltip-format`.
Format replacements:
`{volume}` - Volume in percentage
`{node_name}` - The node's nickname (`node.nick` property)
