SwingSet RunPolicy should be reconciled with cosmic-swingset ChainRunPolicy

[gibson042]

(originally posted by @gibson042 in #10348 (comment))

The extra methods of cosmic-swingset ChainRunPolicy aren't really blockchain-specific, and should probably be added to SwingSet RunPolicy.

...at which point packages/cosmic-swingset/src/computron-counter.js can be rolled into packages/SwingSet/src/lib/runPolicies.js, with the former's computronCounter renamed to something like makeExclusiveCleanupRunPolicy.

Related suggestions:

• chore: let makeRunUtils caller provide run policy #10348 (comment) : "consider splitting the overly-generic beansPerUnit parameter to be less directly coupled to cosmic-swingset chain parameters" ({ beansPerUnit, vatCleanupBudget } → { computronScale, computeLimit, vatCreationCost, vatCleanupBudget })