Add `make test-unit` target.
Add `make test-unit` target.

Unit tests don't actually require separate building, so rename `test` to
`test-unit`, remove that dependency and speed up test running time by a bit.
Also remove a duplicate PHONY declaration.

Keep around the `test` target for CI, and make it also run the `verify`
target.

sallyom/online-hibernation,sallyom/online-hibernation