Use IValueTaskSource in PipeStream on Windows

[stephentoub]

FileStream was recently overhauled, including using an IValueTaskSource as part of its support for async operations. PipeStream used an almost exact copy of the code FileStream had previously been using; we should similarly update PipeStream to use an IValueTaskSource implementation, either the exact same one, sharing the code, or something similar in spirit. This will help to reduce allocations with PipeStream.

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Issue Details

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FileStream was recently overhauled, including using an IValueTaskSource as part of its support for async operations. PipeStream used an almost exact copy of the code FileStream had previously been using; we should similarly update PipeStream to use an IValueTaskSource implementation, either the exact same one, sharing the code, or something similar in spirit. This will help to reduce allocations with PipeStream.

Author:	stephentoub
Assignees:	-
Labels:	area-System.IO, tenet-performance
Milestone:	6.0.0

[carlossanlop]

@manandre Thank you for your contribution! I'd assign this issue to you but GitHub doesn't let me unless you participate in the discussion here. Consider the issue yours.

[manandre]

@carlossanlop Thanks for assigning me to this issue.