math: Implement new Vec swizzle method

[noisegul]

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Motivated by the previously associated TODO note.
This strategy allows for generalized arbitrary swizzling instead by using an enum and the builtin @shuffle function.

• old: a.yzx()
• new: a.swizzle(.y, .z, .x)

[slimsag]

Thanks @noisegul - this looks like a good approach