Adjust examples to the new detector handling

[EricMEsch]

The recent updates that moved the

    enum DetectorType {
      kGermanium,
      kOptical,
      kScintillator,
    };

Out of RMGHardware broke the examples and the custom written c++ code, as the enum is now no longer part of the RMGHardware class. This went past the tests, as there is no extra compiled code in the tests.

I am not sure if the rest of the way the registration should be handled is still the same, but this works. Compile tested but did not check the output.

[ManuelHu]

I am not sure if the rest of the way the registration should be handled is still the same, but this works. Compile tested but did not check the output.

should have stayed the same. The naming has only been changed to break a circular dependency... (and the "typical" way to break that is impossible: one cannot forward declare nested structs/enums; thanks C++)