This pull request add compatibility to CarpetX to Multipole.

https://bitbucket.org/einsteintoolkit/einsteinanalysis/pull-requests/22

Due to the nature of Multipole, its actual functionality remains unchanged, only test cases require changes due to interacting with CoordinatesX and CartGrid3D.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2786/support-carpetx-in-multipole