Non-standard attribute

[roblabla]

Most swipc data represents how a vanilla Nintendo console behaves, but adding non-standard things (twili, atmosphere extensions) would be nice. However, we'd need a way to visually distinguish them on SwIPC-docs.

We should add a @nonstandard attribute that can be attached either to an interface (in which case the interface itself, all of its cmds, and the service name, are non-standard) or to a particular function inside a standard interface (for atmosphere extensions).

[misson20000]

The attribute should also have a parameter specifying the relevant project(s)