Rust SDK 2 SQLite `Value` helpers

[itowlson]

I'm updating the docs for the Rust SDK.

It seems like we used to support ValueParam::Text("something") but the new Value enum only accepts owned Strings e.g. Value::Text("something".to_owned()). Is it possible to make this more flexible, e.g. adding a From(&str) implementation? (or am I missing where we already have a friendly conversion method)

[rylev]

This is because we are more heavily relying on wit-bindgen for generating the SDK so we unfortunately have fewer "niceties" , but we do have the benefit of no longer having two types ValueParam and ValueResult for the same logical type.

This means we can't go back to how things were before without going back to redefining all of the types ourselves and having Param and Result variants of the same logical type.