cli: Add command line interface to combine/split uhex files.

[carlosperate]

Simple CLI implementation to be able to combine and split universal hex files.
This will be useful to be able to combine it with other tools, like the Radio Bridge and Activity Tracker.

Example usage:

uhex combine --v1 input_intel.hex --v2 input_intel.hex -u output_universal.hex

uhex split -u universal_input.hex