Switch to the new SQL/JSON PG17 JSON functions

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PG17 introduced support for the standardized SQL/JSON functions, specifically JSON_VALUE() and JSON_QUERY() - we should consider switching to those when the compatibility mode is set to PG17. One notable advantage is that e.g. JSON_VALUE() allows specifying the return type; we currently use the -> operator and wrap the result in a cast, which may be less efficient and also doesn't support JSON-specific conversions (for example, getting a binary out of JSON is likely to do base64 decoding automatically, without us having to manually take care of it).

Another possibility is to switch from jsonb_to_recordset to the new JSON_TABLE().