BEP Idea: Add MongoDB query and aggregation API endpoint support.

[elmadj]

Currently, the asset search endpoint is a basic text search feature which imposes a large computational time to be able to retrieve assets with complex search criteria.
Similarly, asset aggregations have to go through a text search and perform the actual computation on the client side.

This proposal aims to create two new endpoints:

• A MongoDB JSON query endpoint which allows a client to perform an arbitrary search on assets. Benefiting from the power of MongoDB search and indexes.

• An aggregation query which allows a client to perform aggregations on MongoDB and push the computation to the server.

These new features are implemented in a Pull Request.
BEP Upgrade proposed by Via Science Inc.
Note: Contributors agreement signed.