extensions/markdown-language-features/src/languageFeatures/copyPaste.ts/PasteEditProvider/_getNewFileName
class PasteEditProvider:	private async _getNewFileName(document: vscode.TextDocument, file: vscode.DataTransferFile): Promise<vscode.Uri> {
		const root = Utils.dirname(document.uri);

		const ext = path.extname(file.name);
		const baseName = path.basename(file.name, ext);
		for (let i = 0; ; ++i) {
			const name = i === 0 ? baseName : `${baseName}-${i}`;
			const uri = vscode.Uri.joinPath(root, `${name}${ext}`);
			try {
				await vscode.workspace.fs.stat(uri);
			} catch {
				// Does not exist
				return uri;
			}
		}
	}