ClientRpc and ServerRpc decorators should give an error if attached to a non-NetworkBehaviour class method

Is your feature request related to a problem? Please describe.
I'm finding it easy to accidentally add [ClientRpc] or [ServerRpc] methods to MonoBehaviour-derived classes, where clearly they won't do anything. This leads to a bunch of confusion while I try to figure out what's wrong with the networking only to do the forehead-slap when I notice that the class hasn't been switched to NetworkBehaviour.

Describe the solution you'd like
At a minimum, a runtime error with a descriptive error message would be helpful. Something like "FooClientRpc was added to a class that doesn't derive from NetworkBehaviour - as a result, FooClientRpc will never be called."

Better would be a similar error logged when in the editor. Compile-time errors would be ideal if possible, of course.

Describe alternatives you've considered
Beyond "vigilance" (which can be assumed doesn't work), if it becomes a more serious issue then I'd have to rig some sort of linting rule to catch this.

La issue non indica file, test o punti di ingresso. Inizia individuando la gestione dei decorator ClientRpc e ServerRpc e il modo in cui viene verificata l’ereditarietà da NetworkBehaviour; definisci e testa una diagnostica per i metodi nelle classi che non derivano da NetworkBehaviour, incluso il comportamento richiesto a runtime o nell’editor.