DaCe opt: corners (dace.map and/or stree merge)

[FlorianDeconinck]

We should be able to merge all copy corners into one single kernel / map.

First try out a copy_corners wrote in a single dace.map instead of a stencil. Then potentially we can leverage the stree. to do those merge auto-magically. Tal from LLNL will have ideas.

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xTeam: LLNL / SPCL
DoD: Corners in pyFV3 are effectively made faster.