As stated in issue #61137, the new API for project delete is should be improved.
Moreover I also propose to extend this API with support for project
copy/rename/move.

Summary of proposed changes:
-move ProjectOperations from org.netbeans.api.project to
 org.netbeans.spi.project.support. Reasons are that:
 1. only a limited number of clients should use the class (for NB
    probably only two: the default project operations implementation and
    the J2EE project)
 2. this class is not strictly necessary: the client can go through
    the lookup itself
-do top level interfaces from the DeleteOperationImplementation (and
 added two new CopyOperationImplementation, MoveOperationImplementation).
-move the default delete(/copy/rename/move) operation into the
 Project UI API.
-change performClean to notifyDeleting
-add COMMAND_COPY, COMMAND_RENAME and COMMAND_MOVE and corresponding methods in
ActionsFactory.
-add ReferenceHelper.fixReferences to help resolve broken references after
copy/rename/move.

I am attaching:
-copy-move-api.diff showing only API changes
-copy-move-full.diff showing also implementation (the impl. is not completelly
finished)
-test.jar with tests for the default project delete/copy/rename/move implementation