flexible.Struct - a FlexibleStruct/Array alternative

Hello. I’m hoping for some feedback on this alternative to the FlexibleStruct/FlexibleArray pull request. Its similar but adds lots of stuff like a user Layout API, and size and offset helpers in addition to a Self API (values(), slice(), sliceField(), sliceLen()). I haven’t benchmarked it yet 😅 but its designed to be faster than the orignal with flexible fields after Layout fields and sorted by alignment. WIth this, we can simd prefix sum the aligned sizes in constant time. It ...