Check for project existence in Project Maintainers list

https://github.com/cncf/foundation/blob/main/project-maintainers.csv houses all the top-level maintainers for all CNCF projects. This is used to do things like allow access to CNCF's Service Desk.

We should validate that a project exists in this list and has at least one maintainer listed.

Start by reviewing the linked project-maintainers.csv source and locating the existing project validation entry point in CLOMonitor. Confirm how project names are matched, then ensure validation reports projects missing from the list or having no listed maintainer. Done means both conditions are checked against the source data.

Written by the indexing model from the issue text.