Add MarkEdit.openFile for opening files.

Change getFileDataURI to getFileObject.

Add MarkEdit.getFileDataURI for binary files.

Add MarkEdit.getDirectoryPath for standard directories.

Add MarkEdit.translationService for translation.

Add a few file system APIs.

Add MarkEdit.runService for running system services.

Expose @codemirror/lang-markdown and @codemirror/autocomplete.

Reduce unnecessary nullability.

Add generative language model APIs.