`sql::Value` is an integral part of `surrealdb`. It's the internal type used by our storage layer. Because of this, we do a lot of converting between this type and native Rust types. Currently this conversion is done through `JSON` using the `serde_json` crate because we do not have our own custom data format implementation. This works because `SQL` is a superset of `JSON`. This, however, means that this conversion is lossy and can cause surprises in some cases. For example expecting record IDs to be deserialized into a `String` instead of its corresponding Rust native type.
This change implements a custom data format around `sql::Value` and introduces a `to_value` function that facilitates that conversion.
Due to a bug in msgpack-rust (https://github.com/3Hren/msgpack-rust/issues/86), in order to have correct serialization<->deserialization of data, we need to ensure all fields are serialized even when empty. This will affect the output size of the data, but will ensure that once serialized, the data is deserialized without issue.
