New BitVector64 and/or revised BitArray

[ericwood8]

Summary
Currently in C# there is a BitVector32() struct on stack and a BitArray() dynamic heap. Developers have had to manually create their own data structures for 64-bit and to enhance the properties and methods. Can you make a 64-bit and 128-bit (or maybe dynamically chooses native bit of the box) version of BitVector or a BitArray that works on the stack? Could AMD help with making optimizations to AMD chips?

Motivation
GOAL 1- Can there be speed ups of existing code so that the compiler detects non-fancy coding (maybe of Boolean or integer or short character segments) and chooses to use this new struct under the hood? (This could be a way to improve performance of C# compared to other languages.)
GOAL 2- Improve properties and methods especially in non-bit specific ways (meaning BitVector32 wants you to interact with it with only masks)
GOAL 3- Do this as struct if we know it is static length and within the size.
GOAL 4 - Perhaps use the new Span functionality to improve performance.
GOAL 5 - Low priority - Perhaps work with chip makers (such as AMD) to improve performance.
GOAL 6 - Very low priority - Perhaps this would help porting C++ code that has bit operations on 64-bit to C#.

Planning
I like some of the properties and methods found under the BigInteger:
https://learn.microsoft.com/en-us/dotnet/api/system.numerics.biginteger?view=net-8.0

I like his commentary of what are issues with BitVector32 and BitArray. Also he attempts to fix it.:
https://www.jacksondunstan.com/articles/5126

Here is another developer adding the BitVector64:
https://www.codeproject.com/Tips/838362/A-bit-Bit-Field-in-Csharp

I suggest glancing at other vendors that do something similar:
Unity.Collections has NativeBitArray, BitField32, BitField64

Perhaps it could be implemented under the hood with hardware intrinsics such as Vector128 or whatever.