API-based functionality for managing configurations for usage across multiple clients

[bzeiss]

Feature proposal

Describe the issue

rascsi-web has functionality for loading, saving and deleting profiles. Those profiles provide preconfigured slot-to-image mappings that allows allows to quickly recall certain configurations. The current implementation is not interoperable with multiple clients, but is implemented directly in the web interface. It would probably be good if this functionality is moved into the core so that other client implementations (like the Android app or the hardware UI in development #382) can make shared use of these profiles (i.e. a profile is created with the web app and then loaded using the Android app or the hardware UI etc.) through the protobuf API.

[rdmark]

As an additional shortcoming of the current setup where rascsi-web is responsible for reading configurations, is the fact that you have to have run the rascsi-web script in order for the config to be loaded. This is not ideal for folks who want to run an entirely headless solution without the overhead of a webapp running.