[WIP] Asktell/optimas gen test

[jlnav]

• Simple sampler

Iterate on VOCS -> gen_specs SSoT:

• Medium-term Optimas should only be test dependency
• sim_id shouldn't need to be set as a gen.out - manager will handle.
• do we continue auto-wrapping x0, x1 into the (x, float, 2) dtype ? It should be okay if the sim expects the x1 and x2.
• persis_in can be determined from vocs.
• Maybe auto-swap to only_persistent_gens alloc upon vocs being provided?