* flows: initial diagram implementation
* web: install flowchart.js, add flow diagram page
* web: adjust diagram colours for dark mode
* flows: add permission checks for diagram
* flows: fix formatting
* web: fix formatting for web
* flows: add fix when last stage has policy
* flows: add test for diagram
* web: flows/diagram: add support for light mode
* flows: make Flows's Diagram API return json, add more tests and fix swagger response
