Adjust Mongodb plugin to filter costs

[timsanwald]

Is your feature request related to a problem? Please describe.
We are sharing a MongoDB organisation and have multiple projects in it. In a particular Opencost deployment I just want to see the costs of some of the MongoDB instances. Right now its just possible to configure the Organisation and have all costs of it.

Describe the solution you'd like
Provide some configuration parameter to filter the invoices e.g. by tags, by project name or id

Describe alternatives you've considered

Additional context

[ameijer]

thanks @timsanwald

cc @cliffcolvin , we have had similar issues with our internal stuff.