This fixes 2 related issues:
* Now that the bor consensus engine is required for queries it can't be
created based on the pretense of a db directory, but must be based on
chain config read from the db. Using the DB presence causes Bor to get
instantiated for non bor chains which breaks.
* At the moment eth_calls on a remote daemon don't check Bor headers
prior to calling the EVM code as it was just using a fake ETHash
instance - which performs ETH header validation only.
The current version is mostly working but needs adapting to perform lazy
initialization of the engine.
Whitelisting calculation of the roothash should not be dependent on the
bor api running. This will not always be the case, for example when
erigon is configured with a separate rpc deamon.
To fix this the calculation has been moved to Bor.
Additionally the redundant Bor API code has been removed as this is not
called by any code and the functionality looks to have migrated to the
turbo/jsonrpc package.
