serial-lcr: move device driver code from src/lcr/ to src/hardware/

serial-lcr: move device driver code from src/lcr/ to src/hardware/

Keep the ES51919 chip support in the src/lcr/ directory, and move device
driver specific code to the src/hardware/serial-lcr/ directory. Implement
the same driver layout for LCR meters as is used for DMM devices.

This also addresses a few issues in the serial-lcr driver: Unbreak --get
and --show, do process a few LCR packets after probing the device, to
gather current parameter values. Keep sending meta packets when these
parameters change during acquisition, like the previous implementation
did. Use common code for frame/time limits.

Note that although LCR meters usually operate with AC to classify L/C/R
components, one of the officially supported modes is DC resistance.
Which means that an output frequency of 0 is not just a fallback when
packet parsing fails, it's also a regular value of the freq parameter.
List all supported frequencies including DC in strict numerical order.

Although all currently supported devices use the same ES51919 chip, the
implementation is prepared to support other devices which use different
LCR meter chips as well. The list of known equivalent circuit models and
output frequencies is kept in src/lcr/ chip support. It's assumed that
one LCR packet communicates the data for all channels/displays similar
to the serial-dmm driver implementation.