Support changing chunk size & chunking scheme in settings

[samlhuillier]

Chunk size is currently 500. This should not be hardcoded and users should be able to change this in settings.

Implementation:

1. Add the property in store config for chunk size
2. Use chunk size in Chunking.ts
3. Add a page in settings to change this chunk size

An extension of this would be to change the chunking scheme; right now, markdown headings with # start a new note. Some users may not want that.

[milaiwi]

Inside Chunking.ts, should we create a new Store<StoreSchema>() or modify the function to take in a pre-existing store, similar to how other functions do it?

[milaiwi]

Any update on this?