SpringConfig->@MatsClassMapping: Create an optional (like @Override) annotation for the ProcessContext inject

[stolsvik]

To more quickly see, and be reminded of, the automatic injection of ProcessContext in a @MatsClassMapping, there have been voiced interest in an annotation.

Since I don't need that to do the injection, it would be optional, like @Override is. Basically, purely a "decorative" annotation, for human reading. Could potentially catch if it was annotated on a wrong field, though.

E.g.:

@MatsProcessContext
private ProcessContext<Dto> _processContext