This adds proper support for data types other than double to CarpetX, also for GPUs.

It introduces a helper class AnyVectorthat can hold any data type (similar to gdata in CarpetLib), as well as a number of switch statements to handle openPMD's typed output routines. 

I am told that very new versions of openPMD-api lets one call the internal un-typed output routine, but at the time this code was written, that was not yet possible, and thus may not be possible on all cluster installed copies of openPMD.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2836/add-support-for-different-data-types-to