Update do_insert in MongoDB tab

[Lalith-Sagar-Devagudi]

Description

This update introduces two significant improvements to the do_insert function within the MongoDB tab of the superduperdb package:

1. Previously, the datatype check within the conditional statements was incomplete, leading to potential issues when non-string data types were passed. I've fixed this by importing the DataType class and explicitly checking if the datatype is an instance of DataType.

2. I've modified the function signature of do_insert to include schema as an optional parameter with a default value of None.

Related Issues

[TEST-USE] Transfer learning #1967

Checklist

• Is this code covered by new or existing unit tests or integration tests?
• Did you run make unit-testing and make integration-testing successfully?
• Do new classes, functions, methods and parameters all have docstrings?
• Were existing docstrings updated, if necessary?
• Was external documentation updated, if necessary?