Feature Request: flag grouping and ordering

[everett1992]

By default oclif alphabetizes command flags in help output. I would like options to organize flags.

• by preserving my defined order
• by section or group with heading

For instance, here's sort --help, where ordering options are separated from other options.

Ordering options:

  -b, --ignore-leading-blanks  ignore leading blanks
  -d, --dictionary-order      consider only blanks and alphanumeric characters
  ...
Other options:

      --batch-size=NMERGE   merge at most NMERGE inputs at once;
                            for more use temp files
  -c, --check, --check=diagnose-first  check for sorted input; do not sort
  ...

[mdonnalley]

You can do this now by using the helpGroup property on the flag definitions