CHIA-1945 Avoid computing a transactions filter with just reward coins when the filter is not requested from get_block_header

[AmineKhaldi]

Purpose:

We tend to use get_block_header in paths where we don't care about the transactions filter, by passing empty additions and removals, yet when a transaction block contains reward coins, we end up computing a non-empty one. Now make it explicit that we care about the transactions filter by sending a tuple of additions and removals.

Current Behavior:

We generate a non-empty transactions filter when we get called with a transaction block that has reward coins, even if we pass empty additions and removals, which we usually do to signal not caring about the filter.

New Behavior:

We generate an empty transactions filter unless we're passed a tuple of additions and removals, in which case we account for them, as well as reward coins, in the computation of the transactions filter.

[arvidn]

what do you think of passing Optional[tuple[Collection[Coin], Collection[Coin]]] instead? That way, you explicitly pass None as additions and removals to indicate that you're not interested in the transaction filter.

One issue with adding a separate tx_filter: bool parameter is that you can pass in empty lists (because you don't care) but forget to pass in tx_filter=False.

[AmineKhaldi]

what do you think of passing Optional[tuple[Collection[Coin], Collection[Coin]]] instead? That way, you explicitly pass None as additions and removals to indicate that you're not interested in the transaction filter.

One issue with adding a separate tx_filter: bool parameter is that you can pass in empty lists (because you don't care) but forget to pass in tx_filter=False.

That's a good point. Done.