[WIP] Chunked array for ByteBuffer

[TIHan]

Still a work in progress for this issue: #7982

This one is a bit tricky. Effectively it's writing data to a memory stream that is constantly getting resized and re-allocated when the buffer size limit is reached. Therefore, we need to solve this by having a memory stream backed by chunked byte arrays. There is nothing built into the core libraries that solve this for us; we need to build it ourselves.

Right now I'm using Span for part of it as it helped me reduce some cognitive load. We can take it out if it's an issue. I know I'm having some trouble with the System.Memory package and the compiler.

• Decide whether or not to use Span (Could use ArraySegment instead)
• Remove use of ToArray on the ChunkedArray in places we know have the ability to go passed the LOH. ByteMemory Fixed LOH byte array allocations in the IDE from metadata #7971 may need to get merged first before we figure this out.
• Cleanup - figure out what's public and private for members on ChunkedArray and ChunkedArrayBuilder

Possible Alternatives:

• Investigate and use https://github.com/microsoft/Microsoft.IO.RecyclableMemoryStream instead
• Use System.Reflection.Metadata.BlobBuilder (I don't know if this is a good idea because it might be specific for reading assembly metadata and not for general use, @tmat could tell us.)
• Write to disk

Current impl is based on ideas from System.Reflection.Metadata.BlobBuilder.

[TIHan]

Closing as I think this is too complicated. Will only go back to it if there is no other choice.

[AlgorithmsAreCool]

This concept kinda overlaps with ReadOnlySequence. Perhaps merging those concepts and building a SequenceWriter could save some code on the consumption side of things?

There are a few reference implementations floating around for such a thing.