Query/JSON: throw better exception when expecting array of objects, but the JSON represents a single object

[maumar]

pointed out by @aldrashan here: #33101 (comment)

Basically when the mismatch happens we throw Invalid token type: 'StartObject'. We should throw a better exception.

[roji]

@maumar we could consider this, but note that there's a big variety of cases where the JSON in the database doesn't correspond to what the user tells us, and I doubt that the regular JSON deserializer (in System.Text.Json) does a significantly better job here (it may be worth checking).