feat: add __experimental_info export to core

[davidmurdoch]

This is an internal and private feature for Truffle. Truffle needed a way to programmatically get the list of chains Ganache fully supports in order to enable the dry-run feature for those chains.

This introduces a new experimental and private (this will likely change in a future release!) __experimental_info export:

Readonly<{
  version: string,
  fork: Readonly<{
    /**
     * Chains Ganache is known to be compatible with. Operations performed
     * locally at historic block numbers will use the Ethereum Virtual Machine
     * OPCODEs, gas prices, and EIPs that were active at the time the historic
     * block originally took place.
     */
    knownChainIds: number[],
  }>
}>

[haltman-at]

The method seems good enough for me! Earlier you made it sound like there might be a more expansive thing with more info about the various chains, which might be nice for later, but if that's a bunch more work, well, knownChainIds does the job! :)

[davidmurdoch]

Oh yeah, we could potentially stuff a whole bunch of interesting stuff in here in the future.

[haltman-at]

Seems good to me! Maybe more can go here in the future, but this should be good enough for now.