message: Better name for cell content mode as well.
diff: @@ -683,9 +683,9 @@ export type $NotebookCellTextDocumentFilter = NotebookCellTextDocumentFilter & {
  export interface NotebookCellTextDocumentSyncFeatureShape {
  mode: 'cellContent';
  - sendOpen(textDocument: vscode.TextDocument): Promise<void>;
  - sendChange(event: vscode.TextDocumentChangeEvent): Promise<void>;
  - sendClose(textDocument: vscode.TextDocument): Promise<void>;
  + sendDidOpenTextDocument(textDocument: vscode.TextDocument): Promise<void>;
  + sendDidChangeTextDocument(event: vscode.TextDocumentChangeEvent): Promise<void>;
  + sendDidCloseTextDocument(textDocument: vscode.TextDocument): Promise<void>;
  }
  class NotebookCellTextDocumentSyncFeatureProvider implements NotebookCellTextDocumentSyncFeatureShape {
  @@ -731,17 +731,17 @@ class NotebookCellTextDocumentSyncFeatureProvider implements NotebookCellTextDoc
  }
  }
  - public async sendOpen(textDocument: vscode.TextDocument): Promise<void> {
  + public async sendDidOpenTextDocument(textDocument: vscode.TextDocument): Promise<void> {
  const provider = this.client.getFeature(DidOpenTextDocumentNotification.method).getProvider(textDocument);
  return provider !== undefined ? provider.send(textDocument) : Promise.reject(new Error(`No open provider found for notebook cell document ${textDocument.uri.toString()}`));
  }
  - public async sendChange(event: vscode.TextDocumentChangeEvent): Promise<void> {
  + public async sendDidChangeTextDocument(event: vscode.TextDocumentChangeEvent): Promise<void> {
  const provider = this.client.getFeature(DidChangeTextDocumentNotification.method).getProvider(event.document);
  return provider !== undefined ? provider.send(event) : Promise.reject(new Error(`No change provider found for notebook cell document ${event.document.uri.toString()}`));
  }
  - public async sendClose(textDocument: vscode.TextDocument): Promise<void> {
  + public async sendDidCloseTextDocument(textDocument: vscode.TextDocument): Promise<void> {
  const provider = this.client.getFeature(DidCloseTextDocumentNotification.method).getProvider(textDocument);
  return provider !== undefined ? provider.send(textDocument) : Promise.reject(new Error(`No close provider found for notebook cell document ${textDocument.uri.toString()}`));
  }
  