Add scrollbar.showScrollbar

Fixes #5676

src/common/services/OptionsService.ts

@@ -32,7 +32,7 @@ export const DEFAULT_OPTIONS: Readonly<Required<ITerminalOptions>> = {
   logLevel: 'info',
   logger: null,
   scrollback: 1000,
-  scrollbar: {},
+  scrollbar: { showScrollbar: true },
   scrollOnEraseInDisplay: false,
   scrollOnUserInput: true,
   scrollSensitivity: 1,

src/common/services/Services.ts

@@ -311,6 +311,7 @@ export interface ITerminalQuirks {
 }
 
 export interface IScrollbarOptions {
+  showScrollbar?: boolean;
   showArrows?: boolean;
 }