Allow `--` to signal end of argument parsing

[sbc100]

IIUC is fairly normal for tools that run other tools to use -- to signal the end of argument parsing for the outer tool.

e.g. node --arg-for-node -- myfile.py --arg-for-js-program

Would it be easy/possible for hyperfine to do the same to avoid the need to quote the command line e.g.

$ hyperfine -- ls -la

Instead of:

$ hyperfine 'ls -la'