Properly set up ModuleCache and use cached instantiation model

[jayz22]

#1359 introduced ModuleCache which instantiates all contracts in the storage and caches their VM. However there are no code path exercising it yet.
This issue tracks the followup work needed to

• properly initialize the cache
• calibrate the cached instantiation cost
• charge the cost VmCachedInstantiation for the cache hit path
• add tests

[graydon]

This is all done