Add a project index to Tenant

This adds a data structure holding all of the projects in a tenant
organized for fast lookup either by fully or partially qualified
project name.

This will obsolete some tenant data structures which are partially
duplicative.  They will be removed in a future change.

Story: 2000953
Change-Id: I9002e36409544a9e5665f22a72bfa980e818ac91
3 files changed