[Copilot] `azldev package list` support for new flag to exclude "group" from output

[christopherco]

Issue Description

Currently after running azldev package list -a -O json, group field will be present in the output as a part of each package. @sameluch and I were talking and it would be nice to have an optional flag to exclude the group field from the output.

Expected Changes

Add a new CLI flag to azldev package list like --omit-group so the json output from azldev package list -a -O json --omit-group will output not contain the "group" field.

Additional Context

No response