[ADF-2930] general purpose "Empty Page" component (#3296)

* empty content component

* fix selector name

* style fixes

* cleanup code

* docs for empty content

* update docs

* update docs

* use typography for icon

* layout fixes for Login (ported from ACA)

lib/core/components/empty-content/empty-content.component.html

@@ -0,0 +1,6 @@
+<div class="adf-empty-content">
+    <mat-icon class="adf-empty-content__icon">{{ icon }}</mat-icon>
+    <p class="adf-empty-content__title">{{ title | translate }}</p>
+    <p class="adf-empty-content__subtitle">{{ subtitle | translate }}</p>
+    <ng-content></ng-content>
+</div>

lib/core/components/empty-content/empty-content.component.scss

@@ -0,0 +1,33 @@
+@mixin adf-empty-content-theme($theme) {
+
+    $config: mat-typography-config();
+    $foreground: map-get($theme, foreground);
+
+    .adf-empty-content {
+        color: mat-color($foreground, text, 0.54);
+        display: flex;
+        flex-direction: column;
+        align-items: center;
+
+        &__icon {
+            font-size: mat-font-size($config, display-3);
+            height: mat-font-size($config, display-3) !important;
+            width: mat-font-size($config, display-3) !important;
+        }
+
+        p {
+            line-height: 0;
+        }
+
+        &__title {
+            font-size: 18px;
+            font-weight: 600;
+        }
+
+        &__subtitle,
+        &__text {
+            font-size: 14px;
+            font-weight: 300;
+        }
+    }
+}

lib/core/components/empty-content/empty-content.component.ts

@@ -0,0 +1,39 @@
+/*!
+ * @license
+ * Copyright 2016 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Component, ChangeDetectionStrategy, ViewEncapsulation, Input } from '@angular/core';
+
+@Component({
+    selector: 'adf-empty-content',
+    templateUrl: './empty-content.component.html',
+    styleUrls: ['./empty-content.component.scss'],
+    changeDetection: ChangeDetectionStrategy.OnPush,
+    encapsulation: ViewEncapsulation.None,
+    host: { class: 'adf-empty-content' }
+})
+export class EmptyContentComponent {
+
+    @Input()
+    icon = 'cake';
+
+    @Input()
+    title = '';
+
+    @Input()
+    subtitle = '';
+
+}