[Docs] Add FilePathUrlConverter notebook

Following on from OpenAssetIO/OpenAssetIO#1117 add a Jupyter Notebook
illustrating the usage of `FilePathUrlConverter`.

This is in no way complete, and was used as part of a live demo in
sprint review. It seems like useful documentation nonetheless and worth
keeping in the repo.

Signed-off-by: David Feltell <[email protected]>

Author: feltech