These replace `wait*` functions from `docker_utils_test.go` and work
more or less like other `cli` functions.
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Add some required command operators to the `cli` package, and update
some tests to use this package, in order to remove a few functions
from `docker_utils_test.go`
Signed-off-by: Vincent Demeester <vincent@sbr.pm>