* Added procs to get and store block witness in db and add generate-witness cli flag.
* Completed initial implementation of block witness storage.
* Added test to verify witness is persisted to db after call to persistBlock.
* Update getBlockWitness to return witness using Result type.
* Make generate witness parameter hidden.
* Update experimental rpc test to do further validation on proof responses.
* Enable zero value storage slots in the witness cache data so that proofs will be returned when a storage slot is updated to zero. Refactor and simplify implementation of getProofs endpoint.
* Improve test validation.
* Minor fixes and added test to track the changes introduced in every block using a local state.
* Refactor and cleanup test.
* Comments added to test and account cache fixes applied to account ledger.
* Return updated storage slots even when storage is empty and add test to build.
* Fix copyright and remove incorrect depth check during witness building in writeShortRlp assertion.
* Add premix persist tool to Makefile to build as separate binary.
* Fix rootBytes.len > 0 assertion defect in HexaryTrie by adding call to com.db.compensateLegacySetup().
* Run hardForkTransition before executing transactions in getBlockWitness.
* Improve logging and add help message.
* Retry requests for block data.
* Return slots when verifying witness regardless of code length.
* Prevent AccountCache WitnessData codeTouched from being reset.
* Default to using {wfNoFlag} for witness flags in tests to allow running with data from before EIP170.
* Add additional json files to experimental JSON RPC test.
* Use HTTP RPC server in tests.
* Add test to check that block witness contains bytecode.
* Completed draft implementation of witness JSON-RPC endpoints for portal network bridge.
* Updated Nimbus RPC configuration to support enabling experimental endpoints.
* Moved witness verification tests.
* Added json test for getProof.
* Added main procs to new tests to fix test suite.
* Added getBlockWitness test to blockchain json test suite.
* Added tests for experimental RPC endpoints and improved the API to support returning state proofs from before or after block execution.
* Correctly rollback transaction in getBlockWitness proc.
* Initial implementation of eth_getProof endpoint.
* Implemented generation of account and storage proofs.
* Minor fixes and additional tests.
* Refactor getBranch code into a separate file.
* Improve usage of test data.
* Fix copyright year.
* Return zero hash for codeHash and storageHash if account doesn't exist.
* Update copyright notice and moved trie key hashing to inside getBranch proc.
Both types are not safe and require validation/conversion
from rpc implementer.
This PR change it to safer types and delegate the conversion
and validation to the rpc library.