Support Deserialize<T>(Stream) directly

YamlSerializer.Deserialize<T>(Stream);

Implementation details

Currently, YamlParser can only read ReadOnlySequence. Therefore, we want to create a ReadOnlySequence from a Stream.

The easiest way to do this is to read the entire Stream and create a large byte array. (e.g. MemoryStream).

However, the way is not the best.

Streams may be network I/Os or file I/Os.
Perhaps the I/O arrive in chunks, from start to end, in sequence.
It is wasteful to make these chunks into huge byte array.
- Heap allocation
- Copy to byte sequence

So, it is better to make chunks of Stream as ReadOnlySequenceSegment .

MemoryPack probably does exactly this. I implemented most of mine based on this.