WIP: markets 0.6.0 with non-blocking retrieval

[hannahhoward]

Goals

Utilize new payment channel functionality to allow retrievals to proceed w/o waiting for chain operations more frequently, as long as there are funds in channel for vouchers

Implementation

• Adjust the node adapter to the new node functions, which also align more closely to PayAPI funcs
  • note one part is held up on one more piece of functionality from @dirkmc
• Remove use of direct references to PayChMgr in retrieval client adapter wherever possible (fewer assumptions of running in same process the better)
• Add the ability when adding funds to the payment channel to restart any retrieval deals that have stalled on insufficient funds. While this is unlikely to happen as long as retrieval deals are the only consumers of payment channels, once we add other consumers, they might use the retrieval funds and cause deals to run out of money. This allows us to add more money to a payment channel manually as a way to unstick these deals

[arajasek]

Pulled into #3603