Add Parlia consensus engine for Binance Smart Chain support (#3086)

* Add Parlia consensus engine for Binance Smart Chain support

* Leave RamanujanBlock as nil in params/config.go

* Run `go fmt` on files needing it

* Add comment for PoSA

* Remove empty branches and ineffectual assignments in parlia.go

* Remove commented imports

* Fix compilation error

* Remove EIP155Signer in transaction_signing.go

* Fix compilation issue

* Fix go fmt issues

* Remove Ramanujan from print statement

* Remove references to EthAPIBackend approach

* Fix Finalize method across consensus engines

* Run go fmt

* More linting

* Remove more changes

* remove a comment

* Remove unneeded hashing function

* Remove bytes check and fix actual vs expected mistake