Windows: Use anonymous pipes in Command
When setting `Stdio::pipe` on `Command` we want to create an anonymous pipe that can be used asynchronously (at least on our end). Usually we'd use [`CreatePipe`](https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-createpipe) to open anonymous pipes but unfortunately it opens pipes for synchronous access. The alternative is to use [`CreateNamedPipeW`](https://learn.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-createnamedpipew) which does allow asynchronous access but that requires giving a file name to the pipe. So we currently have this awful hack where we attempt to emulate anonymous pipes using `CreateNamedPipeW` by attempting to create a unique name and looping until we find one that doesn't already exist.
The better option is to use the lower level [`NtCreateNamedPipeFile`](https://learn.microsoft.com/en-us/windows/win32/devnotes/nt-create-named-pipe-file) (which is used internally by both `CreatePipe` and `CreateNamedPipeW`). This function wasn't documented until a few years ago but now that it is it's ok for us to use it.
try-job: *msvc*
try-job: *mingw*
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