Seed TestVM with predictable testing values at construction

[alexytsu]

Currently constants such as TEST_VM_RAND_ARRAY and TEST_FAUCET_ADDR are used as static consts in the TestVM's stack. These are also duplicated and used in the fil_actors_integration_tests crate to make assertions during test execution.

They should be deduplicated a possible solution is to reference GensisSpec usage #1345 (comment)

[anorth]

Related: #1371

[anorth]

This is part of a general need to inject/configure all externally-provided values into the VM. E.g. the circulating supply is a value provided to the VM by its host (Lotus). Follow a pattern like Primitives to bring all similar values under control of the test author.

[anorth]

The ref FVM has

• Externs, which are some functions that call out to the host for things like chain randomness
• Machine constants, which are values provided at construction for things like base fee and circulating supply

I think there could have been just a single concept here, but let's just follow the same design which will make the integration easier.