Use correct `boolean` type for JSON Schema creation

[crisaltmann]

Hello,

After this PR which modifies the boolean type on JsonSchemaObject, I started to receive the error below when trying to add a schema validator on a collection.

log: {"ok": 0.0, "errmsg": "Unknown type name alias: bool", "code": 2, "codeName": "BadValue"}

My mongo version is 5.0. The BSON type is bool but the Json type remains boolean