Merge from vscode merge-base (#22769)

* Merge from vscode merge-base

* Turn off basic checks

* Enable compilation, unit, and integration tests

extensions/markdown-language-features/src/languageFeatures/copyPaste.ts

@@ -0,0 +1,29 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { tryGetUriListSnippet } from './dropIntoEditor';
+
+export function registerPasteSupport(selector: vscode.DocumentSelector) {
+	return vscode.languages.registerDocumentPasteEditProvider(selector, new class implements vscode.DocumentPasteEditProvider {
+
+		async provideDocumentPasteEdits(
+			document: vscode.TextDocument,
+			_ranges: readonly vscode.Range[],
+			dataTransfer: vscode.DataTransfer,
+			token: vscode.CancellationToken,
+		): Promise<vscode.DocumentPasteEdit | undefined> {
+			const enabled = vscode.workspace.getConfiguration('markdown', document).get('experimental.editor.pasteLinks.enabled', true);
+			if (!enabled) {
+				return;
+			}
+
+			const snippet = await tryGetUriListSnippet(document, dataTransfer, token);
+			return snippet ? new vscode.DocumentPasteEdit(snippet) : undefined;
+		}
+	}, {
+		pasteMimeTypes: ['text/uri-list']
+	});
+}