refactor: rename service_manager.go and remove unused CommandRunner interface

Rename service_manager.go to commands_service_manager.go to follow the
established naming pattern with other command files.

Remove the unused CommandRunner interface from commands.go since it's not
being used anywhere in the codebase. Clean up unused imports.

This improves consistency in file naming and removes dead code.

cmd/cli/commands_service.go

@@ -21,6 +21,17 @@ import (
 	"github.com/Control-D-Inc/ctrld"
 )
 
+// filterEmptyStrings removes empty strings from a slice
+func filterEmptyStrings(slice []string) []string {
+	var result []string
+	for _, s := range slice {
+		if s != "" {
+			result = append(result, s)
+		}
+	}
+	return result
+}
+
 // ServiceCommand handles service-related operations
 type ServiceCommand struct {
 	serviceManager *ServiceManager