Implement serialization for `ScalarValue::FixedSizeBinary`

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

@maxburke's PR added ScalarFixedSizeBinary support: #3911

However, it did not implement the serialization code to send ScalarValue::FixedSizeBinary over the network

Describe the solution you'd like

Fill out the code in datafusion/proto/src/to_proto.rs

            scalar::ScalarValue::FixedSizeBinary(_, _) => {
                return Err(Error::General(
                    "FixedSizeBinary is not yet implemented".to_owned(),
                ))
            }

And add a test for round trip serialization

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[alamb]

Should be a good first issue as there are plenty of other examples to follow along

[retikulum]

It looks interesting. Can you assign it to me?

[alamb]

See also- #3612 - the serialization code is a bit of a mess now but hopefully we can get it better