This pull request introduces significant changes to the Viction API backend to support querying by both block number and block hash. The changes include adding new methods to handle BlockNumberOrHash types and updating existing methods to use these new methods.

Methods updated:

• eth_getBalance
• eth_getStorageAt
• eth_getCode
• eth_getTransactionCount
• eth_call
• eth_estimateGas

Support for BlockNumberOrHash:

• eth/api_backend.go: Added HeaderByNumberOrHash and StateAndHeaderByNumberOrHash methods to handle queries by either block number or block hash. [1] [2]
• les/api_backend.go: Added HeaderByNumberOrHash and StateAndHeaderByNumberOrHash methods to the LES API backend. [1] [2]

Updates to PublicBlockChainAPI:

• internal/ethapi/api.go: Updated methods such as GetBalance, GetCode, GetStorageAt, Call, EstimateGas, and GetTransactionCount to use StateAndHeaderByNumberOrHash. [1] [2] [3] [4] [5] [6] [7] [8] [9]

Backend Interface Update:

• internal/ethapi/backend.go: Updated the Backend interface to include the new HeaderByNumberOrHash and StateAndHeaderByNumberOrHash methods.

Test Updates:

• internal/ethapi/api_test.go: Added new methods to the test backend to support HeaderByNumberOrHash and StateAndHeaderByNumberOrHash. Updated tests to use BlockNumberOrHash. [1] [2] [3]

Miscellaneous:

• internal/ethapi/api.go: Fixed import ordering.
• internal/ethapi/api_test.go: Fixed import ordering. [1] [2]
• internal/ethapi/backend.go: Fixed import ordering.

Referrence:

• internal/ethapi: support block number or hash on state-related methods ethereum/go-ethereum#19491