Use ij1-patcher in fiji.Debug

This pull request relies on https://github.com/imagej/ij1-patcher/pull/7 being addressed first. After that, we can toss our old, stale method to debug ImageJ 1.x plugins inside an Integrated Development Environment overboard, in favor of instantiating a `LegacyEnvironment`, asking it to add the appropriate class path and be done with it. Every improvement in ij1-patcher will automatically benefit `fiji.Debug`'s `run()` and `runFilter()` methods.