Allow statically sized array as record dimension

[bernhardmgruber]

LLAMA allows statically sized arrays inside Records as a shorthand notation. However, it seems using a statically sized array directly as record dimension fails to compile.

using RecordDim = float[3];
using ArrayDims = ...;
using Mapping = llama::mapping::AoS<ArrayDims, RecordDim>;
...

Investiage this and add a unit test.