feat(sqlite): add -> and ->> JSON operators

[KekmaTime]

Add support for SQLite's -> and ->> JSON extraction operators.

The -> operator extracts a JSON subcomponent and returns it as a TEXT JSON representation (always returns Json type, never Jsonb).

The ->> operator extracts a JSON subcomponent and returns it as an SQL TEXT value (unwrapped).

partially completes #4366

[KekmaTime]

@weiznich CI is failing on deprecated Command::cargo_bin() in example tests (unrelated to my changes). The new cargo_bin! macro doesn't work with clippy. #[allow(deprecated)] also didn't help. How should I fix this example tests to pass CI?

[weiznich]

@KekmaTime I've opened #4845 to address this. Let's merge that PR first and then just rebase this one on top.

[weiznich]

Seems like this collides with the same operators as defined in the postgres backend if both backends are enabled. I think we should be able to workaround that by rather move the operators + the methods from the extension trait in a central location instead of duplicating them for both backend.

We would need to move:

diesel/diesel/src/pg/expression/operators.rs

Lines 46 to 52 in 143b254

	__diesel_infix_operator!(
	RetrieveAsObjectJson,
	" -> ",
	__diesel_internal_SameResultAsInput,
	backend: Pg
	);
	infix_operator!(RetrieveAsTextJson, " ->> ", Text, backend: Pg);

To https://github.com/diesel-rs/diesel/blob/main/diesel/src/expression/operators.rs#L610

Also we need to move the trait methods to a new trait in a new json_trait_methods file here:

https://github.com/diesel-rs/diesel/tree/main/diesel/src/expression_methods

[KekmaTime]

Ack, will update 👍