EPS: own sub-device, entities removed when the option is off

The 36 EPS entities were mixed into the main inverter device, which on a
hybrid means hundreds of entities in one list. They now use device_group
and appear under "<hub> EPS", linked to the inverter with via_device - the
same pattern the battery pack devices already use. The redundant EPS
prefix is dropped from the names, which the device now provides. Keys and
entity ids are unchanged.

With the Emergency Power Option (EPS) switched off the entities are not
created and the device is removed from the registry instead of lingering
forever.

EPS Mute becomes a switch (write 0x43, readback 0xB7) instead of a
read-only sensor, matching the cloud app.

Stacked on the sub-device infrastructure PR.

Author: Bl00d-B0b