[pallet-revive] Update gas encoding (#6689)

Update the current approach to attach the `ref_time`, `pov` and
`deposit` parameters to an Ethereum transaction.
Previously we will pass these 3 parameters along with the signed
payload, and check that the fees resulting from `gas x gas_price` match
the actual fees paid by the user for the extrinsic.

This approach unfortunately can be attacked. A malicious actor could
force such a transaction to fail by injecting low values for some of
these extra parameters as they are not part of the signed payload.

The new approach encodes these 3 extra parameters in the lower digits of
the transaction gas, approximating the the log2 of the actual values to
encode each components on 2 digits

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Co-authored-by: GitHub Action <[email protected]>
Co-authored-by: command-bot <>