Support for Mongodb

Have a look at my piece of work for MongoDB in [hariprasadraja/mongodb](https://github.com/hariprasadraja/mongoqb).

I hope It will be helpful if I integrate it with yours.

awaiting for your replay.

The issue proposes integrating a MongoDB query builder from an external repository. First, examine the linked repository to understand its API and structure. Then, review the rql codebase to see how SQL query building is currently implemented and where a MongoDB adapter might fit. Determine what 'integration' means—whether it's a new driver, a plugin, or a separate package. The scope is large and requires deep familiarity with both codebases.

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