`GeometrySet` contains at most one component of each type.
Previously, a map was used to make sure that each component
type only exists once. The overhead of a map (especially with
inline storage) is rather large though. Since all component types
are known at compile time and the number of types is low,
a simple `std::array` works as well.
Some benefits of using `std::array` here:
* Looking up the component of a specific type is a bit faster.
* The size of `GeometrySet` becomes much smaller from 192 to 40 bytes.
* Debugging a `GeometrySet` in many tools becomes simpler because
one can easily see which components exists and which don't
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