fix: allow renaming old applications to new format

0.22.0 changed allowed values for app names, making it more difficult for users to fix their app names - you need to either downgrade+rename or recreate the app. The `apps:rename`  command can now rename these old applications to the new standard.

Also drop some app name verification from internal commands. Duplicate verification doesn't help much, and though it isn't excessively slow, it does prevent us from running commands against old apps that exist.

Refs #4267

plugins/common/common.go

@@ -416,10 +416,10 @@ func UcFirst(str string) string {
 	return ""
 }
 
-// IsValidAppName verifies app name format
+// IsValidAppName verifies that the app name matches naming restrictions
 func IsValidAppName(appName string) error {
 	if appName == "" {
-		return fmt.Errorf("APP must not be null")
+		return errors.New("Please specify an app to run the command on")
 	}
 
 	r, _ := regexp.Compile("^[a-z0-9][^/:_A-Z]*$")
@@ -430,10 +430,27 @@ func IsValidAppName(appName string) error {
 	return errors.New("App name must begin with lowercase alphanumeric character, and cannot include uppercase characters, colons, or underscores")
 }
 
-// VerifyAppName verifies app name format and app existence"
+// isValidAppNameOld verifies that the app name matches the old naming restrictions
+func isValidAppNameOld(appName string) error {
+	if appName == "" {
+		return errors.New("Please specify an app to run the command on")
+	}
+
+	r, _ := regexp.Compile("^[a-z0-9][^/:A-Z]*$")
+	if r.MatchString(appName) {
+		return nil
+	}
+
+	return errors.New("App name must begin with lowercase alphanumeric character, and cannot include uppercase characters, or colons")
+}
+
+// VerifyAppName checks if an app conforming to either the old or new
+// naming conventions exists
 func VerifyAppName(appName string) error {
-	if err := IsValidAppName(appName); err != nil {
-		return err
+	newErr := IsValidAppName(appName)
+	oldErr := isValidAppNameOld(appName)
+	if newErr != nil && oldErr != nil {
+		return newErr
 	}
 
 	appRoot := AppRoot(appName)