rename users and groups extensions

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

extensions/users/cmd/user/main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"os"
+
+	"github.com/owncloud/ocis/v2/extensions/users/pkg/command"
+	"github.com/owncloud/ocis/v2/extensions/users/pkg/config/defaults"
+)
+
+func main() {
+	if err := command.Execute(defaults.DefaultConfig()); err != nil {
+		os.Exit(1)
+	}
+}