(MODULES-10514) Remove use of version_powershell task in install task

[beechtom]

This removes the use of the version_powershell task in the
install_powershell task. Previously, this task was used to determine
whether the puppet-agent package was already installed. However, some
features used to run the script and parse its output are not available
in versions of powershell older than 3.0.

The install_powershell task instead uses behavior similar to the
version_powershell task by checking the system's registry entries to
check if the puppet-agent package is installed.

[puppetcla]

CLA signed by all contributors.

[donoghuc]

What powershell < 3 features do not work? Can we figure out a way around it? Seems like we would want to update the version task to work with powershell < 3 if we are testing against it.

[donoghuc]

Windows PowerShell
Copyright (C) 2009 Microsoft Corporation. All rights reserved.

PS C:\Users\Administrator> $rootPath = 'HKLM:\SOFTWARE\Puppet Labs\Puppet'
PS C:\Users\Administrator>
PS C:\Users\Administrator> $reg = Get-ItemProperty -Path $rootPath -ErrorAction SilentlyContinue
PS C:\Users\Administrator> if ($null -ne $reg) {
>>   if ($null -ne $reg.RememberedInstallDir64) {
>>     $loc = $reg.RememberedInstallDir64+'VERSION'
>>   } elseif ($null -ne $reg.RememberedInstallDir) {
>>     $loc = $reg.RememberedInstallDir+'VERSION'
>>   }
>> }
>>
PS C:\Users\Administrator> if ( ($null -ne $loc) -and (Test-Path -Path $loc) ) {
>>   Write-Output "{`"version`":`"$(Get-Content -Path $loc -ErrorAction Stop)`",`"source`":`"$($loc.replace('\', '/'))`"
}"
>> } else {
>>   Write-Output '{"version":null,"source":null}'
>> }
>>
{"version":"6.12.0","source":"C:/Program Files/Puppet Labs/Puppet/VERSION"}
PS C:\Users\Administrator> $psversiontable

Name                           Value
----                           -----
CLRVersion                     2.0.50727.8806
BuildVersion                   6.0.6002.18111
PSVersion                      2.0
WSManStackVersion              2.0
PSCompatibleVersions           {1.0, 2.0}
SerializationVersion           1.1.0.1
PSRemotingProtocolVersion      2.1


PS C:\Users\Administrator>

[beechtom]

The version task works in powershell < 3. The issue is how the version task is used by the install task. Currently, the install task uses the $PSScriptRoot variable to get the directory that both scripts were saved to and then uses the ConvertFrom-Json cmdlet to parse the output from the version task. Neither of these are available in powershell < 3.

There are ways to get the parent directory and parse json in powershell < 3, but it seems overly complex for what the install task needs to do, which is just determine if the agent is installed at all, not determine its version or the source.