fix: handle casting primitive array with $elemMatch in bulkWrite()

[vkarpov15]

Fix #14678

Summary

Right now, casting $elemMatch on a primitive array in bulkWrite() throws an error. That's because we have some logic for casting $elemMatch in the primitive array schematype that really belongs in the document array schematype, but in the past we've just thrown all conditional handling logic for arrays onto the primitive array schematype.

With this PR, we now have separate $conditionalHandlers for document array schematype vs primitive array schematype. And the offending logic that caused #14678 is only on the documentarray schematype.

Examples