Create REST APIs for everything

It would be useful for the product owner meeting to write a guideline on how to implement REST APIs. This would include stuff like

• naming of things
• locations and code guidlines
• url names and pathes
• permissions
• endpoint documentation
• allowed (http) methods
• used content types
• available authentication types
• anything else

added part::backend label

Closed in favour of #700 (closed)

closed