feat: ethclient gas estimation blocknumber param

[tynes]

This commit adds the blocknumber param to the ethclient's
gas estimation function. This lets users choose the block number
to estimate gas against. If nil is passed, then pending will
be used to preserve existing behavior.

Technically, a block tag can be used here but a blocknumber
is used for simplicity. Gas estimation takes similar params
as eth_call, and there are two different functions on the
ethclient for doing eth_call - one by block number and
one by block hash.

The simulated backend is not updated to take into account
the block number parameter, it will still use the pending
state. That functionality can be added in the future if
desired.

Closes #25001

[tynes]

It looks like the tests failed on a flake

not ok 1 TestSnapGetStorageRanges
# peering failed: handshake failed: bad handshake: ðtest.Error{err:(*errors.errorString)(0x210a66c0)}

[fjl]

The test failure you observed there is not related.

[fjl]

We cannot make this change because it modifies the Go API in a backwards-incompatible way.

The only way to achieve this is with new API surface. For example, we could add EstimateGasAtBlock as a new method.

However, I also wonder, what's the point of estimating the gas usage of a transaction at any block other than "latest" or "pending".

[holiman]

@fjl made some good points, and this PR has been inactive since June. Closing.

Thanks for making an effort!