change userName to match what the azure account display name is (#11484)

* change userName to match what the azure account display name is

* Handle undefined value

src/sql/base/browser/ui/selectBox/selectBox.ts

@@ -197,6 +197,10 @@ export class SelectBox extends vsSelectBox {
 		return this._selectedOption;
 	}
 
+	public get label(): string | undefined {
+		return this._dialogOptions.find(s => s.value === this._selectedOption).text;
+	}
+
 	public get values(): string[] {
 		return this._dialogOptions.map(s => s.value);
 	}