Add support for external bundle validators

internal/cmd/operator-sdk/bundle/validate/cmd.go

@@ -95,7 +95,11 @@ To validate a bundle against the validator for Good Practices specifically, in a
 
 To validate a bundle against the (alpha) validator for Deprecated APIs specifically, in addition to required bundle validators:
 
-  $ operator-sdk bundle validate ./bundle --select-optional name=alpha-deprecated-apis --optional-values=k8s-version=1.22	
+  $ operator-sdk bundle validate ./bundle --select-optional name=alpha-deprecated-apis --optional-values=k8s-version=1.22
+
+To validate a bundle against an external validator, in addition to required bundle validators:
+
+  $ operator-sdk bundle validate ./bundle --alpha-select-external /path/to/external-validator[:/path/to/optional-second-validator]
 	`
 )
 
@@ -139,11 +143,15 @@ func NewCmd() *cobra.Command {
 			if err != nil {
 				logger.Fatal(err)
 			}
-			if err := result.PrintWithFormat(c.outputFormat); err != nil {
+			failed, err := result.PrintWithFormat(c.outputFormat)
+			if err != nil {
 				logger.Fatal(err)
 			}
 
-			logger.Info("All validation tests have completed successfully")
+			// if a test failed don't print that it was successful
+			if !failed {
+				logger.Info("All validation tests have completed successfully")
+			}
 
 			return nil
 		},