Refactor Password validator into mixin

no issue
- PasswordValidator was only adding a function to the base class but it introduced a confusing inheritance hierarchy that's easier to reason about when it's a mixin instead
- swapped the `this.properties =` and `this._super()` calls in the `init` function of `new-user` so that the default can actually be applied
  - previously the BaseValidator `init` method was doing `this.properties = []` which meant the default fallback in extended classes wouldn't work

ghost/admin/app/validators/mixins/password.js

@@ -1,4 +1,4 @@
-import BaseValidator from './base';
+import Mixin from '@ember/object/mixin';
 import validator from 'npm:validator';
 
 const BAD_PASSWORDS = [
@@ -13,7 +13,7 @@ const BAD_PASSWORDS = [
 ];
 const DISALLOWED_PASSWORDS = ['ghost', 'password', 'passw0rd'];
 
-export default BaseValidator.extend({
+export default Mixin.create({
     /**
     * Counts repeated characters if a string. When 50% or more characters are the same,
     * we return false and therefore invalidate the string.

ghost/admin/app/validators/new-user.js

@@ -1,11 +1,12 @@
-import PasswordValidator from 'ghost-admin/validators/password';
+import BaseValidator from './base';
+import PasswordValidatorMixin from './mixins/password';
 import validator from 'npm:validator';
 import {isBlank} from '@ember/utils';
 
-export default PasswordValidator.extend({
+export default BaseValidator.extend(PasswordValidatorMixin, {
     init() {
-        this._super(...arguments);
         this.properties = this.properties || ['name', 'email', 'password'];
+        this._super(...arguments);
     },
 
     name(model) {

ghost/admin/app/validators/reset.js

@@ -1,9 +1,13 @@
-import PasswordValidator from 'ghost-admin/validators/password';
+import BaseValidator from './base';
+import PasswordValidatorMixin from './mixins/password';
 import validator from 'npm:validator';
 import {isBlank} from '@ember/utils';
 
-export default PasswordValidator.create({
-    properties: ['newPassword'],
+const resetValidator = BaseValidator.extend(PasswordValidatorMixin, {
+    init() {
+        this.properties = this.properties || ['newPassword'];
+        this._super(...arguments);
+    },
 
     newPassword(model) {
         let p1 = model.get('newPassword');
@@ -20,3 +24,5 @@ export default PasswordValidator.create({
         this.passwordValidation(model, p1, 'newPassword');
     }
 });
+
+export default resetValidator.create();

ghost/admin/app/validators/user.js

@@ -1,9 +1,13 @@
-import PasswordValidator from 'ghost-admin/validators/password';
+import BaseValidator from './base';
+import PasswordValidatorMixin from './mixins/password';
 import validator from 'npm:validator';
 import {isBlank} from '@ember/utils';
 
-export default PasswordValidator.create({
-    properties: ['name', 'bio', 'email', 'location', 'website', 'roles'],
+const userValidator = BaseValidator.extend(PasswordValidatorMixin, {
+    init() {
+        this.properties = this.properties || ['name', 'bio', 'email', 'location', 'website', 'roles'];
+        this._super(...arguments);
+    },
 
     isActive(model) {
         return (model.get('status') === 'active');
@@ -121,3 +125,5 @@ export default PasswordValidator.create({
         }
     }
 });
+
+export default userValidator.create();