Propose "allowLocal" open dialog option API

Part of #131138

src/vs/workbench/services/extensions/common/extensionsApiProposals.ts

@@ -56,6 +56,7 @@ export const allApiProposals = Object.freeze({
 	scmActionButton: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmActionButton.d.ts',
 	scmSelectedProvider: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmSelectedProvider.d.ts',
 	scmValidation: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.scmValidation.d.ts',
+	showLocal: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.showLocal.d.ts',
 	tabInputTextMerge: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.tabInputTextMerge.d.ts',
 	taskPresentationGroup: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.taskPresentationGroup.d.ts',
 	telemetry: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.telemetry.d.ts',

src/vscode-dts/vscode.proposed.showLocal.d.ts

@@ -0,0 +1,19 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+// https://github.com/microsoft/vscode/issues/131138
+
+declare module 'vscode' {
+
+	export interface OpenDialogOptions {
+		/**
+		 * Controls whether the dialog allows users to select local files via the "Show Local" button.
+		 * Extensions that set this to `true` should check the scheme of the selected file.
+		 *
+		 * TODO: Workspace extensions already get only `file` scheme URIs back from the dialog. Should we ignore `allowLocal` for them?
+		 */
+		allowLocal?: boolean;
+	}
+}