[fixes #50105529] Show workfiles larger than 1/8 MB in truncated, readonly mode with a warning message.  Otherwise code mirror will break

- add content() method to HdfsEntry
- add isPartialFile() method to Workfile
- convert HdfsShowFileView to ReadOnlyTextContent, use model.content() instead of model.get("content")
- add PartialWorkfileContentDetails view
- add constructorName to various views
- add auto_scroll_horizontal css style