Db folder sources and related remove compiler warnings (#2673)
* Aristo: Rename `Hash256` -> `Hash32`
* CoreDb: Rename `Hash256` -> `Hash32`
* Ledger: Rename `Hash256` -> `Hash32`
* StorageTypes: Rename `Hash256` -> `Hash32`
* Aristo: Rename `Blob` -> `seq[byte]`, `keccakHash` -> `keccak256`
* Kvt: Rename `Blob` -> `seq[byte]`
* CoreDb: Rename `Blob` -> `seq[byte]`, `keccakHash` -> `keccak256`
* Ledger: Rename `Blob` -> `seq[byte]`, `keccakHash` -> `keccak256`
* CoreDb: Rename `BlockHeader` -> `Header`, `BlockNonce` -> `Bytes8`
* Misc: Rename `StorageKey` -> `Bytes32`
* Tracer: `Hash256` -> `Hash32`, `BlockHeader` -> `Header`, etc.
* Fix copyright header