This adds logic to
`PartialWitnessActor::validate_partial_encoded_state_witness()` that
checks that the height is greater than the current final head height
(as is done in `Client::process_chunk_state_witness()`), and
not more than five ahead of the current head height, similar to what's
done in `EncodedChunksCache::height_within_horizon()`

For now we read the head and final head heights directlly from the
database, but in the future this should be changed so that we make a
request to the client for this info

Related issue: near#11301