ENH: bubble up deps during orch sub builds

[CJ-Wright]

Many times orch sub builds have similar requirements to the parent build. It would be nice to run the (non-orch) installers once per section. This essentially requires the orch sub build to know it is a sub build and propagate the requirements up. This might not work for build requirements, since the build may require one of its deps to be installed and running (which requires the runtime deps to be installed). But this should be ok for runtime requirements.

[CJ-Wright]

This might be ok for build if we run things in order (eg conda set(deps), pip install set(deps), then install all the sources from scratch)

[CJ-Wright]

ping @mwaddellcolumbia

[CJ-Wright]

So this got rather complex fast. I think I understand what has to be done better now.

1. Create a node which represents the code to be installed with its install command
2. Create parent nodes which represent the direct deps
3. Repeat 1 and 2 for all orch nodes recursively until no orch nodes remain
4. Handle any clashes by order of precedence (default vs bleeding (bleeding wins)) then by preference (orch then conda then pip)
5. If safe merge all pip and conda installs for the build requirements and install the packages specified
6. If aggro merge all pip and conda installs for all the requirements
7. Run orch installs in topo order, maybe I can get away with sorting by path length to the first node