Add directly_supplies_drains

[dosumis]

Use case:

Currently supplies is used for indirect relationships. The definitions fits this:

Relation between an arterial structure and another structure, where the arterial structure acts as a conduit channeling fluid, substance or energy.

HubMap VCCF is curating direct supplies/drains relationships between the capillary networks and the tissues they supply/drain

Parking this ticket here for discussion. Consider moving to RO if agreement reached.

@anitacaron @emquardokus @GriffinWeber

[github-actions]

This issue has not seen any activity in the past 6 months; it will be closed automatically one year from now if no action is taken.

[aleixpuigb]

Parking this ticket here for discussion. Consider moving to RO if agreement reached.

If I'm not wrong, I think there was an agreement to add this object property. Should I move it to RO?