EIP-7742 - gas calculation using target_blobs_per_block

[siladu]

PR description

The approach uses the Optional targetBlobsPerBlock field to trigger the new behaviour rather than explicitly checking the fork.

targetBlobsPerGas is sent to Besu via newPayloadV4 (see #7840) where it will be added to the block header (see #7808).

CancunGasCalculator.computeExcessBlobGas was pulled up as default method on GasCalculator interface so it can be inherited by PragueGasCalculator as well as future gas calculators.

It was not desirable to leave CancunGasCalculator untouched and override in PragueGasCalculator (the typical pattern for forks) because the method signature needed to change in order to avoid leaking conditional fork behaviour to the callers (BlobGasValidationRule and ExcessBlobGasCalculator).

In GasCalculator, the presence of the dynamic targetBlobsPerBlock (on the parent header) causes its value to replace the static CancunGasCalculator.TARGET_BLOB_GAS_PER_BLOCK (equivalent to 3 blobs).

Instead of the hardcoded value from 4844 (TARGET_BLOB_GAS_PER_BLOCK), parentTargetBlobGas is now calculated via blobGasCost(parentTargetBlobsPerBlock)

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Part of #7605

Implemented as written in https://github.com/ethereum/EIPs/blob/a78f470331f2150aa1640f348ab4343127d212af/EIPS/eip-7742.md

but note there are further changes likely coming: ethereum/EIPs#8994

Spec for https://eips.ethereum.org/EIPS/eip-7742 was finalized with no further changes

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