Define flows for "Save" button

[gavin-k-lee]

As part of targetting no/low code solutions and their users, we should implement clickable buttons to run certain commands, like renku save, or git add -all; git commit -m 'message'; git push. Possible breakdown of cases (TBC with devs):
https://www.figma.com/file/x1YHYNJA5PCHYztmAIvvMO/Save-button?node-id=0%3A1

Simplify flows for initial implementation, set scope for future rounds.

Could we lean into a Git GUI for this?

Acceptance criteria

• confirm all possible cases for this flow

[ciyer]

We do not need to wait for the bigger redesign of the sessions flow to implement this, we can already put this into the UI and let users make use of it.

[ciyer]

SwissDataScienceCenter/renku-notebooks#762 should be merged at the end of the current sprint. That will make the infrastructure necessary for the save button necessary available

[ciyer]

SwissDataScienceCenter/renku-notebooks#1175 describes the logic needed to support this in the UI.