fix(provider/azure): Add Application Name Validator for Azure (#6473)

fix(provider/azure): Add Application Name Validator for Azure.

app/scripts/modules/azure/azure.module.js

@@ -34,6 +34,7 @@ module.exports = angular
     require('./securityGroup/securityGroup.reader').name,
     require('./image/image.reader').name,
     require('./cache/cacheConfigurer.service').name,
+    require('./validation/applicationName.validator').name,
   ])
   .config(function() {
     CloudProviderRegistry.registerProvider('azure', {

app/scripts/modules/azure/validation/applicationName.validator.js

@@ -0,0 +1,40 @@
+'use strict';
+
+const angular = require('angular');
+
+import { ApplicationNameValidator } from '@spinnaker/core';
+
+module.exports = angular
+  .module('spinnaker.azure.validation.applicationName', [])
+  .factory('azureApplicationNameValidator', function() {
+    function validateSpecialCharacters(name, errors) {
+      const pattern = /^([a-zA-Z][a-zA-Z0-9]*)?$/;
+      if (!pattern.test(name)) {
+        errors.push(
+          'The application name must begin with a letter and must contain only letters or digits. No ' +
+            'special characters are allowed.',
+        );
+      }
+    }
+
+    function validate(name) {
+      const warnings = [],
+        errors = [];
+
+      if (name && name.length) {
+        validateSpecialCharacters(name, errors);
+      }
+
+      return {
+        warnings: warnings,
+        errors: errors,
+      };
+    }
+
+    return {
+      validate: validate,
+    };
+  })
+  .run(function(azureApplicationNameValidator) {
+    ApplicationNameValidator.registerValidator('azure', azureApplicationNameValidator);
+  });