* Replace Big Data Cluster with big data cluster
Official docs guidance is to use "big data cluster" instead of "Big Data Cluster"
* Use doublequotes and full product name
* open notebooks as untitled files and removed the saving to home directory
* return just filename without extension since save is adding the .ipynb ext
* Changes to open bdc notebooks as untitled docs. Updated tests to align with the changes
* changes: not to show untitled file as dirty and cleaned up tests in notebookService
* changes to address untitled name conflicts with open editors.
* comment cleanup
