Remove unused {{gh-datetime-input}} and related helper

ghost/admin/app/components/gh-datetime-input.js

@@ -1,34 +0,0 @@
-import Component from '@ember/component';
-import boundOneWay from 'ghost-admin/utils/bound-one-way';
-import moment from 'moment';
-import {InvokeActionMixin} from 'ember-invoke-action';
-import {formatDate} from 'ghost-admin/utils/date-formatting';
-import {inject as service} from '@ember/service';
-
-export default Component.extend(InvokeActionMixin, {
-    tagName: 'span',
-    classNames: 'gh-input-icon gh-icon-calendar',
-
-    datetime: boundOneWay('value'),
-    inputClass: null,
-    inputId: null,
-    inputName: null,
-    settings: service(),
-
-    didReceiveAttrs() {
-        let datetime = this.get('datetime') || moment.utc();
-        let blogTimezone = this.get('settings.activeTimezone');
-
-        if (!this.get('update')) {
-            throw new Error(`You must provide an \`update\` action to \`{{${this.templateName}}}\`.`);
-        }
-
-        this.set('datetime', formatDate(datetime || moment.utc(), blogTimezone));
-    },
-
-    focusOut() {
-        let datetime = this.get('datetime');
-
-        this.invokeAction('update', datetime);
-    }
-});

ghost/admin/app/templates/components/gh-datetime-input.hbs

@@ -1,7 +0,0 @@
-{{gh-input datetime
-    id=inputId
-    class=inputClass
-    name=inputName
-    stopEnterKeyDownPropagation="true"
-    update=(action (mut datetime))
-}}

ghost/admin/app/utils/date-formatting.js

@@ -1,21 +0,0 @@
-import moment from 'moment';
-
-const displayDateFormat = 'DD MMM YY @ HH:mm';
-
-// Add missing timestamps
-function verifyTimeStamp(dateString) {
-    if (dateString && !dateString.slice(-5).match(/\d+:\d\d/)) {
-        dateString += ' 12:00';
-    }
-    return dateString;
-}
-
-// Formats a Date or Moment
-function formatDate(value, timezone) {
-    // we output the date adjusted to the blog timezone selected in settings
-    return verifyTimeStamp(value ? moment(value).tz(timezone).format(displayDateFormat) : '');
-}
-
-export {
-    formatDate
-};

ghost/admin/tests/unit/utils/date-formatting-test.js

@@ -1,5 +0,0 @@
-// import {formatDate} from 'ghost-admin/utils/date-formatting';
-
-describe('Unit: Util: date-formatting', function () {
-    it('formats a date or moment');
-});