plugins: add deps_group plugin

[AlexTereshenkov]

❯ pants dependencies //:deps-group-1
requirements#click
requirements#loguru

Works great.

❯ pants --no-pantsd --no-local-cache dependencies cheeseshop/version.py
23:18:15.67 [INFO] deps_group(address="//:deps-group-1", description=None, source=deps-grouping.json, tags=None)
23:18:15.67 [INFO] <class 'internal_plugins.deps_grouping.target_types.DepsGroupTarget'>
//:deps-group-1

Works great.

What's left is to query the dependencies of "//:deps-group-1" and report in the terminal.

But if uncomment

https://github.com/AlexTereshenkov/cheeseshop-query/pull/32/files#diff-4ad71084fd132de6ce6e5a97ddada00df3664bcf6d4d977463be0d11ef7716a0R97

# deps = await Get(Addresses, InferDepsGroupDependenciesRequest(target.get(Dependencies)))

Pants can't find a matching rule.