Updated newsletter management for switch to nullable sender_name

refs https://github.com/TryGhost/Team/issues/1513

- `sender_name` is now nullable with a fallback to the site title
- updated new-newsletter route
  - removed default setting of site title in `senderName` of the new newsletter instance
  - removed extra checks when showing unsaved changes modal as we no longer need to compare the `senderName` attribute against the site title
- updated newsletter preview so the sender name falls back to the site title
- updated sender name input placeholder to show the site title
- removed not-empty validation
- fixed the switch to "multiple newsletter" state in the background of the new-newsletter modal
  - problem was `displayingDefault` getter was looking at all active newsletters rather than just the filtered ones so it was counting the new-but-unsaved newsletter even though it wasn't displayed in the list
  - fixes layout glitch when the new-newsletter modal animates out after cancelling creation

ghost/admin/app/components/modals/edit-newsletter/preview.hbs

@@ -2,7 +2,7 @@
     <div class="gh-members-emailpreview-container">
         <div class="gh-members-emailpreview-faux">
             <p>
-                <span class="strong">{{@newsletter.senderName}}</span> &lt;{{full-email-address (or @newsletter.senderEmail "noreply")}}&gt;
+                <span class="strong">{{or @newsletter.senderName this.settings.title}}</span> &lt;{{full-email-address (or @newsletter.senderEmail "noreply")}}&gt;
             </p>
             <p><span class="dark">To:</span> Jamie Larson &lt;jamie@example.com&gt;</p>
         </div>

ghost/admin/app/components/modals/edit-newsletter/settings.hbs

@@ -33,6 +33,7 @@
                     type="text"
                     class="gh-input miw-100 form-text"
                     value={{@newsletter.senderName}}
+                    placeholder={{this.settings.title}}
                     {{on "input" (fn this.onInput "senderName")}}
                 />
                 <GhErrorMessage @errors={{@newsletter.errors}} @property="senderName" />

ghost/admin/app/components/settings/members-email-labs/newsletter-management.js

@@ -35,7 +35,7 @@ export default class NewsletterManagementComponent extends Component {
     }
 
     get displayingDefault() {
-        return this.statusFilter === 'active' && this.activeNewsletters.length === 1;
+        return this.statusFilter === 'active' && this.filteredNewsletters.length === 1;
     }
 
     @action

ghost/admin/app/routes/settings/members-email-labs/new-newsletter.js

@@ -13,9 +13,7 @@ export default class NewNewsletterRoute extends AdminRoute {
     newsletterModal = null;
 
     model() {
-        return this.store.createRecord('newsletter', {
-            senderName: this.settings.get('title')
-        });
+        return this.store.createRecord('newsletter');
     }
 
     setupController(controller, model) {
@@ -69,19 +67,7 @@ export default class NewNewsletterRoute extends AdminRoute {
     async confirmUnsavedChanges() {
         const newsletter = this.newsletterModal?._data.newsletter;
 
-        if (newsletter?.hasDirtyAttributes) {
-            // first, check that we're not dirty just because we set the default senderName
-            // TODO: remove when senderName is nullable
-            const changedAttributes = newsletter.changedAttributes();
-            const changedKeys = Object.keys(changedAttributes);
-            const onlyDefaultChanged = changedKeys.length === 1
-                && changedKeys[0] === 'senderName'
-                && newsletter.senderName === this.settings.get('title');
-
-            if (onlyDefaultChanged) {
-                return true;
-            }
-
+        if (newsletter && newsletter.hasDirtyAttributes && Object.keys(newsletter.changedAttributes()).length > 0) {
             this.confirmModal = this.modals.open(ConfirmUnsavedChangesModal)
                 .then((discardChanges) => {
                     if (discardChanges === true) {

ghost/admin/app/validators/newsletter.js

@@ -20,11 +20,6 @@ export default BaseValidator.create({
     },
 
     senderName(model) {
-        if (isBlank(model.senderName)) {
-            model.errors.add('senderName', 'Please enter a sender name.');
-            this.invalidate();
-        }
-
         if (!validator.isLength(model.senderName || '', 0, 191)) {
             model.errors.add('senderName', 'Cannot be longer than 191 characters.');
             this.invalidate();

ghost/admin/mirage/scenarios/default.js

@@ -16,7 +16,7 @@ export default function (server) {
         slug: 'site-title',
         description: 'Default newsletter created during setup',
 
-        senderName: 'Site title',
+        senderName: null,
         senderEmail: null,
         senderReplyTo: 'newsletter',