Fixed #3287 adding loading-spinner to markdown cell (#3505)

src/sql/parts/notebook/cellViews/textCell.component.html

@@ -5,6 +5,7 @@
  *--------------------------------------------------------------------------------------------*/
 -->
 <div style="overflow: hidden; width: 100%; height: 100%; display: flex; flex-flow: column">
+	<loading-spinner [loading]="isLoading"></loading-spinner>
 	<div class="notebook-text" style="flex: 0 0 auto;">
 		<code-component *ngIf="isEditMode" [cellModel]="cellModel" (onContentChanged)="handleContentChanged()" [model]="model" [activeCellId]="activeCellId" [hideVerticalToolbar]=true>
 		</code-component>

src/sql/parts/notebook/cellViews/textCell.component.ts

@@ -16,6 +16,9 @@ import { ICellModel } from 'sql/parts/notebook/models/modelInterfaces';
 import { ISanitizer, defaultSanitizer } from 'sql/parts/notebook/outputs/sanitizer';
 import { localize } from 'vs/nls';
 import { NotebookModel } from 'sql/parts/notebook/models/notebookModel';
+import { Emitter } from 'vs/base/common/event';
+import URI from 'vs/base/common/uri';
+import { IOpenerService } from 'vs/platform/opener/common/opener';
 
 export const TEXT_SELECTOR: string = 'text-cell-component';
 
@@ -40,15 +43,20 @@ export class TextCellComponent extends CellView implements OnInit, OnChanges {
 	private _sanitizer: ISanitizer;
 	private _model: NotebookModel;
 	private _activeCellId: string;
+	private readonly _onDidClickLink = this._register(new Emitter<URI>());
+	public readonly onDidClickLink = this._onDidClickLink.event;
+	protected isLoading: boolean;
 
 	constructor(
 		@Inject(forwardRef(() => CommonServiceInterface)) private _bootstrapService: CommonServiceInterface,
 		@Inject(forwardRef(() => ChangeDetectorRef)) private _changeRef: ChangeDetectorRef,
 		@Inject(IWorkbenchThemeService) private themeService: IWorkbenchThemeService,
-		@Inject(ICommandService) private _commandService: ICommandService
+		@Inject(ICommandService) private _commandService: ICommandService,
+		@Inject(IOpenerService) private readonly openerService: IOpenerService,
 	) {
 		super();
 		this.isEditMode = false;
+		this.isLoading = true;
 	}
 
 	//Gets sanitizer from ISanitizer interface
@@ -67,8 +75,14 @@ export class TextCellComponent extends CellView implements OnInit, OnChanges {
 		return this._activeCellId;
 	}
 
+	private setLoading(isLoading: boolean): void {
+		this.isLoading = isLoading;
+		this._changeRef.detectChanges();
+	}
+
 	ngOnInit() {
 		this.updatePreview();
+		this.setLoading(false);
 		this._register(this.themeService.onDidColorThemeChange(this.updateTheme, this));
 		this.updateTheme(this.themeService.getColorTheme());
 		this.cellModel.onOutputsChanged(e => {