This adds a mechanism (read-only) to check for project quota support
in a standard way. This mechanism is leveraged by the tests, which
test for the following:
1. Can we get a quota controller?
2. Can we set the quota for a particular directory?
3. Is the quota being over-enforced?
4. Is the quota being under-enforced?
5. Can we retrieve the quota?
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
