Add a create new item dialog, or improve edit item dialog

[vkbo]

This is a part of #823 regarding modifying the Edit Item dialog.

The fields would be as now with a label and status field, and the layout would also open tags and reference options. These options should at least be used to generate new files, including selecting a template file (see #996). Options would include:

• For new novel files one would choose a header format. For notes this would just be level 1.
• For notes one would have a tag field. This is not used on novel files.
• One could potentially have options to add references, but this may be better suited for a GUI reference editor.