feat: force mojave dark mode support on even though Electron is not built on the 10.14 SDK (#59742)

build/gulpfile.vscode.js

@@ -169,6 +169,7 @@ const config = {
 		name: product.nameLong,
 		urlSchemes: [product.urlProtocol]
 	}],
+	darwinForceDarkModeSupport: true,
 	darwinCredits: darwinCreditsTemplate ? Buffer.from(darwinCreditsTemplate({ commit: commit, date: new Date().toISOString() })) : void 0,
 	linuxExecutableName: product.applicationName,
 	winIcon: 'resources/win32/code.ico',