What

⚠️ for ease of conflict avoidance use based on #3935

Clarification: This PR is mostly scratching an itch of mine & addresses (in my experience) mostly aesthetic problems

Using std::array makes a bunch of codegen things easier. This in turn made it easy to revisit how parameters are passed on constructors.

Previous rationale on now discarded "more like cpp guidelines" approach:

This follows now the usual "common sense" logic that I believe people expect from C++ constructors:

• primitive type, no array: pass by value, copy
• primitive type, fixed size array: pass by const&, copy
• anything that is movable: pass by value, move

The latter one is what we had exclusively before. It's less common in the wild which is why codegen has a bit of rationale in the comments about it.

You might say: "But @Wumpf! Passing large fixed size arrays or structs not by value is important as it avoids a copy, this isn't just aesthetic!". My reply being that from a language lawyer perspective this might be true, but practically there is no such thing as passing structs by value as calling conventions will almost always force (sufficiently large) structs to be passed by reference (with some exceptions to the rule to be fair). Meaning the compiler has a very easy time to optimize both caller and callee even without any inlining what-so-ever ... but I digress... ;)

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