More flexible create_mirror functions

[crtrott]

A customer requires the capability to create a mirror view in CudaSpace for an existing (potentially unmanaged) HostSpace view. The generalization of this is to add a memory space instance argument to create_mirror and create_mirror_view as the place where the new view should be allocated. For create_mirror_view it will return the original view if the memory_space matches that of the original view.

This issue is more a reminder of work done, since I just pushed that thing into develop including a unit-test.

[crtrott]

Merged into master and Trilinos