start splitting BondsTable notebook into separate files

[disberd]

This PR starts splitting the big notebook defining the StructBond into multiple julia files.

Initially the idea was to split this into smaller notebooks that are joined together using the new @fromparent macro from PlutoDevMacros.

Eventually this will be done as part of normal julia files, and @fromparent is probably just gonna be used to test the functionality within a notebook.

It's cool to have all the functionality in a single notebook but it can be quite heavy to load for doing changes, and it can also be quite daunting to look at the huge source file of the notebook, especially with the huge additions (in terms of line numbers) due to cell delimiters, cell order and most importantly Manifest file inclusion

Splitting is done.
Added also a notebook internal to the structbond folder for testing the specific functionality and live changes exploiting the @fromparent macro