Adding support for --experimental_dormant_deps to reduce analysis overhead of virtual_deps

[lgo]

Bazel now has had a dormant deps feature (--experimental_dormant_deps) for a bit now, where:

• You swap attributes and label lists for dormant variables (attr(for_dependency_resolution=), attr.dormant_label(), attr.dormant_label_list() and rule(for_dependency_resolution=)), to allow plumbing through a list of attributes to allow for "dormant" dependency lists and resolution logic
• You implement a materializer (attr.label(materializer=)) to turn the above attributes into an actual dependency

They have a more detailed design doc @ https://docs.google.com/document/d/1BLgnPvWqI1hfUh-rXD6Gw6QqqjwAyJuqhjuAL0t6lBw/edit?tab=t.0 (bazelbuild/bazel#22241)

As I understand, using virtual_deps currently add an analyze-time dependency on all dependencies in the default requirements (from resolutions.from_requirements(...)) which isn't great. Dormant deps is specifically aimed to help reduce this.

Based on my layperson understanding of how to integrate dormant deps, the virtual_deps+ resolutions interface are quite close to what would be required for a clean drop-in implementation of dormant deps.

(I have begun to take a pass at trying to patch this for a monorepo to validate this, so I'll report back with any other notes about obstacles or even a patch)