added input validation in modal when creating a project, area or resource

added command Move to archive
This command will move the currently open project / area / resource to the archive.
If the file is an area, the companion folder (if exists) is also moved. The area note and companion folder are then placed within a subfolder named after the area in your archive folder.
If the file is a project and within a project folder the whole project folder will be moved to the archive

added command Restore from archive
Restores the currently open PARA item or opens a modal in which you can search for an archived project, area or resource that you want to restore.
This change is for a more convenient use of the plugin and is now the only command for restoring archived elements.
If you call the command without a file being open or not archived, the search modal is opened.
If you call the command with a currently open and archived PARA item, this will be restored immediately.

command Create new project now checks whether a project with the same name (case insensitive) already exists in the projects or archive folder

removed command Archive current project

removed command Restore open project from archive

removed command Restore project from archive

add support for project folder structure
You can enable folder structure for projects under the plugin settings Use folder structure for projects.
All corresponding commands can now handle both flat and folder structures for projects.