Use database transactions for Graphql operations

[cesarvarela]

Use database transactions for Graphql operations

Once the migration to our graphql API is completed, we'll have complete control over every interaction with the database, which, among other things, allows us to improve the atomicity of the graphql mutations.

One option is to use MongoDB transactions:

https://www.mongodb.com/docs/drivers/node/current/fundamentals/transactions/

We could create a session in the graphql context and share it in every Mongodb operation.