Add Get-Command to fix missing Install-Module in AzurePowerShell

[onetocny]

Task name: AzurePowerShellV5

Description: Clear-AzContext intermittently removes the Install-Module command from the PowerShell session. As a hot fix we are adding additional call to Get-Command command which recovers the Install-Module command. For more details see attached related issues. The feature might be disabled by setting DISABLE_INSTALL_MODULE_FIX environment variable to true.

Documentation changes required: N

Added unit tests: N

Attached related issues:

• https://portal.microsofticm.com/imp/v5/incidents/details/541745691/summary
• https://dev.azure.com/mseng/AzureDevOps/_workitems/edit/2228771

Checklist:

• Task version was bumped - please check instruction how to do it
• Checked that applied changes work as expected