Add support for apc_modbus

[TimBeekman]

Problem/Motivation

The apc_modbus driver is needed for communication with my UPS

Expected behavior

When i configure the add-on like this:

• name: myups driver: apc_modbus port: auto config:
  • vendorid = 051d

I expected the driver to be loaded.

Actual behavior

The follwoing message is shown in the logs: Can't start /lib/nut/apc_modbus: No such file or directory

Proposed changes

Embed the apc_modbus in the package, or make it possible for the end user to do so

[sinclairpaul]

This looks like it would require a custom NUT build, which isn't something we really want to do.

If you need the functionality I would suggest not using the addon.