(mongo): Properly support array types

[scsmithr]

Context

See https://github.com/glaredb/glaredb/blob/0b27679f92851452307283cb204f9519657e6448/crates/datasource_mongodb/src/infer.rs#L81

Currently just formatting them as a string. Obviously not great if you want to drill down into the array. A challenge here will be types and handling arrays of objects.

Expected

Arrays are properly typed

Actual

Arrays are formatted with a string representation

Impact