Resolve a bundle dependency graph with referenced bundles

[carolynvs]

A bundle dependency has a few ways to define a dependency. For now let's generate a dependency graph for a bundle and its dependencies when all dependencies are defined with a default implementation pinned at a specific version.

Out of scope (will be addressed in separate issues)

• version ranges, and resolving the highest version of a dependency Resolve dependency to using version ranges #2683
• bundle interfaces Evaluate a bundle definition against a bundle interface #2626
• resolving existing installations Resolve a bundle dependency to an existing installation #2627

The dependency graph should take into account dependency outputs, so that when dependency A uses the output of dependency B, A should have a dependency on B in the graph.

ℹ️ Read PEP003 - Advanced Dependencies for context about how dependencies should work, design details, and notes about desired behavior.