`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.
Closes SUR-53
When creating a new context for subqueries or statement clauses, we used to have to clone any variables/values, and freeze the context, so that it could be used across threads and async boundaries.
Now with the new executor pattern for parallel queries, we can pass references instead, improving performance by removing unnecessary cloning of values.
Previously the expression operations happened right-to-left so `1 - 2 - 3 - 4 - 5` was actually calculated as `(1 - (2 - (3 - (4 - (5)))))`. Now the expressions are calculated according to BODMAS, with boolean expressions calculated last.
