Suggestion: Add a command/option to the CLI to list groups

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Feature Request

It would be nice to be able to view all possible groups through the CLI through a command such as poetry list --groups as opposed to having to open the pyproject.toml file.

In addition to the above, if groups supported an additional property description it would make the output of the above recommended command easier for users to interpret by showing the purpose for the group.

An alternative and simpler solution could be to include what group dependencies are in when running poetry show --with dev. For example, the output could be:

coverage       7.2.7     dev      Code coverage measurement for Python

Example

In the pyproject.toml file I could have:

[tool.poetry.group.dev]
description = "Optional dev dependencies used for testing and linting code"
optional = true

[tool.poetry.group.dev.dependencies]
coverage = "7.2.7"
pytest = "7.4.0"
ruff = "0.0.272"

Using the CLI, I could run:

> poetry list --groups

Groups:

dev: Optional dev dependencies used for testing and linting code
    coverage = "7.2.7"
    pytest = "7.4.0"
    ruff = "0.0.272"

Start by reviewing the group definitions in pyproject.toml and the existing poetry list and poetry show CLI behavior. Compare the proposed --groups listing with the alternative poetry show --with dev output, then clarify which approach and description format should be implemented. Done means users can see group membership and purpose from the CLI without opening pyproject.toml.