[feature request] Add Luhmann-style IDs support

[Liu233w]

I name my notes with a classic Luhmann-style ID prefix like:

• 1 IT.md
• 1.1 Large Language Model.md
• 1.1.1 GPT-4o.md
• 1.1.1a The benchmark of GPT-4o.md

This forms a hierarchy that works like a supplement of the link based hierarchy. It would be great if they are considered as part of ExcaliBrain's relationship, so I do not have to manually create links just to mimic those hierarchy.

There are other plugins that does similar thing.