Support monitoring costs at an individual user's level

**Is your feature request related to a problem? Please describe.**
I am frustrated that I am unable to track individual user's costs therefore it is not possible to monitor what user is causing what costs.

**Describe the solution you'd like**
Monitoring of costs at a user level.

**Describe alternatives you've considered**
I have had to create multiple projects so I can have more granular understanding of spending.

**Additional context**
n/a

No files, tests, or entry points are named. Start by locating the existing project-level cost monitoring and the AWS billing data source, then determine how users are represented and what user-level attribution should include. Done means users can view costs attributed to individual users with clear aggregation and validation.

Written by the indexing model from the issue text.