Export/import notes in folder structure to keep the organization Notea provides

[themedleb]

I think this project needs the ability to export/import notes in folder structure, to keep the consistency of the organization that Notea provides (Notes inside a note ...) when we are exporting and importing .md files.

Example: Let's say we have NoteA and inside it we created NoteB, NoteC, NoteD, ... We can export them like NoteA.md alongside a folder named NoteA and inside that folder we can find NoteB.md, NoteC.md, NoteD.md, ...

Something like this:

Should be exported like this:

And the same thing should happen when importing .md files when organized in folder structure.

I hope this make sense.