(EAI-234): Create mongodb chatbot eval data store MongoDB implementations

[mongodben]

Jira: https://jira.mongodb.org/browse/EAI-234

Changes

• [x] MongoDbCommandMetadataStore
• [x] MongoDbGeneratedDataStore
• [x] MongoDbEvalutionStore
• [x] MongoDbReportStore

Notes

• [x] put changes on top of merged https://github.com/mongodb/chatbot/pull/336 before review

[mongodben]

Implementation looks fine but please space out! I find your style very cramped and hard to read. Thanks!

sure. will adjust. do you know if there is there an eslint rule we could add to enforce spacing? would be good to have some automation here.