(MODULES-8748) Improve pipe reading in the PowerShell Pipe Server
(MODULES-8748) Improve pipe reading in the PowerShell Pipe Server

Previously the powershell manager was modified to read in data from the pipe
in a single call.  However in buffered environments, the pipe will read data
in chunks.  This is supported by the Read method [1]

> This might be less than the number of bytes requested if that number of bytes
> is not currently available

In this commit, the reader will attempt to read all bytes in a single call and
then continue to read the remaining bytes from the pipe until all of the
expected bytes are read.

[1] https://docs.microsoft.com/en-us/dotnet/api/system.io.pipes.pipestream.read?view=netcore-2.0

puppetlabs/puppetlabs-powershell