• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Feature Request

I would like an option to automatically create an extra named "all" that is a combination of all existing extras.
This would make many pyproject.tomls easier to maintain - instead of doing always --extras and specifying each of the extras.
I'm thinking it should be an option under [tool.poetry] or under [tool.extra]. maybe "all" can be a variable name, but it's value is a const that marks it as an all extras specifier? for example

[tool.poetry.extras]
my_all = auto_all

Another idea is to make it smarter for instance:

[tool.poetry.extras]

redis =["redis"]
rabbit =["pika"]
kafka = ["kafka-python"]

small_all = redis + rabbit
all = *

I don't mind submitting a PR, but I would like initial approval for the feature :)