Provide more info to task-scheduler so it can generate more accurate package-task graphs

Currently lage only gives a package graph and task graph separately, so task-scheduler doesn't know when some packages do not contain the tasks in the package.json.

Because of how the final combined package-task is generated, we might over-aggressively run tasks because of this missing info.

For example, if A depends on B and B depends on C:

A -> B -> C

and if only C has the task of special-C-build, when this following is called:

lage special-C-build --scope A

Nothing should be run because "A" doesn't have that task. The expected result is that nothing is run.

Start with the task-scheduler inputs used by lage special-C-build --scope A and compare how the separate package graph and task graph are combined. Trace the A→B→C example to determine where missing task information is lost. Done means the scoped command runs nothing when only C defines special-C-build, with the expected graph behavior covered by verification.