Add Kenwood TK-280,380 support

This started from the latest version of the module attached to
issue #4935 and contains a lot of memory-mapping work from others.

From there, this has been modernized, and cleaned up. The clone
routines have been cleaned up to be deterministic and not dependent on
platform timing behavior (which also makes them way faster). It also
changes from a "show all the memories, assign to groups in the bank
editor" model to one similar to the other Kenwood commercial drivers
in tree (i.e. sub devices for groups).

Tested fairly extensively with a TK-280 and TK-380 (both version 2.0).

Fixes #4935