R1:b950f877c50c

Allow Drydock Blueprints to control "supplemental allocation" behavior so all hosts in an Almanac pool get used

Summary:
Fixes T12145. Ref T13210. See PHI570. See PHI536.

Currently, when you give Drydock an Almanac host pool with more than one host, it never voluntarily builds a second host resource: there is no way to say "maximum X working copies per host" (only "maximum X global working copies") to make the first host overflow, and the allocator tries to pack resources as tightly as possible.

If you…