feat: clone accounts on demand

[thlorenz]

Summary

On demand cloning of accounts.

Details

When a transaction is sent we extract and validate the accounts we find in it that we either:

• don't track yet, i.e. have never cloned
• and or don't find in our ephemeral validator

Those accounts are then cloned from devnet (hardcoded currently) if they are either readonly or
writable and delegated.

Issues/Todo

Since we don't allow new accounts to be created at this point that makes the validator less
usable locally since we cannot run any transactions that want to use accounts whose keypairs
are derived on the fly, i.e. the worm game doesn't work.

We will add a toml format to allow this behavior to be configured at validator start time and
thus it will be possible to allow new accounts to be created.