Display warning when the agent is run in PowerShell Core

[aleksandrlevochkin]

WI

AB#2142810

Problem

The problem typically arises when the agent is started from PowerShell Core and executes a PowerShell task (doesn't matter if the pwsh flag is set or not). In this case the environment variable PSModulePath is copied from PowerShell Core to the agent to Windows PowerShell. Thus, Windows PowerShell attempts to use modules from PowerShell Core locations. This is described in more details here: PowerShell/PowerShell#18530 (comment)

Solution

Added a new knob AZP_AGENT_CHECK_PSMODULES_LOCATIONS. When it is enabled, when the agent is started in PowerShell Core the following message is displayed in the terminal:

The same message is output to the pipeline if it attempts to execute a Windows PowerShell task and the PSModulePath env variable contains some well-known PowerShell Core locations:

Also made some changes to prevent memory problems related to finding parent processes:

• Added a max search depth for the parent process (set to 10)
• The list of processes is now disposed right after doing the necessary checks
• Removed AZP_AGENT_USE_INTEROP_TO_FIND_PARENT_PROCESS knob and related code

Testing

Tested with several Powershell scripts in my test org.
Added L0 tests.

[azure-boards]

✅ Successfully linked to Azure Boards work item(s):

• Bug 2142810

[merlynomsft]

I left some feedback separately; let's discuss

[timbrigham-oc]

@aleksandrlevochkin, @KonstantinTyukalov @kirill-ivlev, @merlynomsft this request is the first time in a long time I've seen an update to to PowerShell3Handler.cs.

Can you kindly take a look at my pull request #4502 which also touches that file? There's a long standing bug there that I would love to see addressed.