add option to make non-metered dynamic vats

[warner]

What is the Problem Being Solved?

For the performance checks that @FUDCo is doing, it would be convenient to allow the creation of non-metered dynamic vats.

This will also help a pattern where the only static vat is the bootstrap vat, and it creates all the other long-lived initial "vat payload" vats as dynamic vats. In that world, these initial dynamic vats should be every bit as powerful as the ones created later for contracts, and if we don't intend to meter some of them, we shouldn't have to pay the overhead of applying the metering transform to their code.

Description of the Design

The E(vatAdminService).createVat(bundle) call will change to take (bundle, options), and metered: false will be honored. If the option is omitted, it defaults to metered: true. If metering is disabled, neither the transform nor the getMeter lexical will be added to the new vat's Compartment, nor will a meterRecord be created for it.

Security Considerations

The ability to create unmetered dynamic vats is a way to escape metering, so it should not be granted to vats which are themselves metered. We currently only give the vatAdminService reference to Zoe, which is not metered. In the future, we might want to create a separate facet for create-metered vs create-unmetered, rather than expressing it as an option, but I think we can wait until we have a need for it.

Test Plan

I'll add unit tests to packages/SwingSet/test/metering/ to cover this new case.