Add serialized size to structs used in gRPC responses

Several endpoints check the number of updates included in the response to stay within `MAX_RESPONSE_PAYLOAD_BYTES` response size. It would be nice to have the serialized size constant associated with the response types to estimate each response size.

This probably requires changes in the protocol first.

> Not for this PR, but it would be good to make this based on the actual serialization sizes. For example, we could have BlockHeader::SERIALIZED_SIZE constant and use it here.
>
> Let's create an issue for this (and include NOTE_RECORD_BYTES in this issue too).

Proposed in: https://github.com/0xMiden/node/pull/1843#discussion_r2998736839