The initial Accel-PPP PPPoE and IPoE implementation both hat
`... interface <name> vlan-id <id>` and `... interface <name> vlan-range <start-stop>`
This is actually a duplicated CLI node
In addition to the rewrite to make use of `get_config_dict()` the CLI is slightly adjusted as specified in T4703.
* Rename vlan-id and vlan-range to simply vlan
* Rename network-mode to simply mode
* Re-use existing common Jinja2 template for Accel-PPP which are shared with PPPoE and SSTP server.
* Retrieve default values via defaultValue XML node