Log Message:
Add cxxopts-3.0.0

This is a lightweight C++ option parser library, supporting the
standard GNU style syntax for options.

Options can be given as:

  --long
  --long=argument
  --long argument
  -a
  -ab
  -abc argument

where c takes an argument, but a and b do not.

Additionally, anything after -- will be parsed as a positional
argument.