Implement rescaleOverlappingGlyphs in webgl

Part of #4969

src/common/services/OptionsService.ts

@@ -44,6 +44,7 @@ export const DEFAULT_OPTIONS: Readonly<Required<ITerminalOptions>> = {
   allowTransparency: false,
   tabStopWidth: 8,
   theme: {},
+  rescaleOverlappingGlyphs: false,
   rightClickSelectsWord: isMac,
   windowOptions: {},
   windowsMode: false,

src/common/services/Services.ts

@@ -234,6 +234,7 @@ export interface ITerminalOptions {
   macOptionIsMeta?: boolean;
   macOptionClickForcesSelection?: boolean;
   minimumContrastRatio?: number;
+  rescaleOverlappingGlyphs?: boolean;
   rightClickSelectsWord?: boolean;
   rows?: number;
   screenReaderMode?: boolean;