Stale proxy URIs after changing resource URI during copy refactoring

[mx990]

When performing a COPY refactoring, the ResourceRelocationContext currently creates the resource with the original URI and then changes the URI of the resource after loading:

xtext/org.eclipse.xtext.ide/src/org/eclipse/xtext/ide/refactoring/ResourceRelocationContext.java

Lines 67 to 75 in d53cb3c

	case COPY:
	Resource copy = resourceSet.createResource(change.getFromURI());
	try {
	copy.load(resourceSet.getURIConverter().createInputStream(change.getFromURI()), null);
	} catch (IOException e) {
	Exceptions.sneakyThrow(e);
	}
	copy.setURI(change.getToURI());
	return copy;

This leaves any proxy URIs in the loaded resource still pointing to the original file. When later resolving the proxies, a second resource for the original file will be created on demand and any local references will be resolved into that resource and not the copy.