Feature: added composite types support

[giuliano-marinelli]

Adds support for the use of Composite Types for MongoDB. Between the commit changes is a modified README that shows how to use the new behaviour implemented. It also pass the jest tests that was modified to include the new behaviour too.

Some fixes added along side the feature:

• Allow MongoDB datasources to use the Array modifier. So the validation was modified.
• Downgraded the package version of jest to ^27.5.1, because incompatibiliy with ts-jest package.

Not implemented yet:

• Validate that the datasource is MongoDB for allow the use composite types.