Add command, pwsh and python subcommands to VC to simplify the execution of 'loose scripts'

[brdeyo]

In order to allow Virtual Client to be better positioned to support script extensions development, the ability to quickly execute a script on the local file system is imperative. The features in this changeset enable a user to provide a PowerShell, Python or random script/command to VC directly on the command line without need to create or modify any profiles.

Usage Examples:

# Scripts in a folder anywhere on the local system.
VirtualClient.exe pwsh "S:\Demo\content.example.package\Invoke-OpenSsl.ps1 -LogDirectory S:\Demo\content.example.package\logs\demo_pwsh" --clean=logs --log-to-file --verbose

VirtualClient.exe python "S:\Demo\content.example.package\execute_openssl.py1 S:\Demo\content.example.package\logs\demo_python" --clean=logs --log-to-file --verbose

# Scripts in the VC packages folder
VirtualClient.exe pwsh ".\packages\content.example.package\Invoke-OpenSsl.ps1 -LogDirectory .\logs\demo_pwsh" --clean=logs --log-to-file --verbose

VirtualClient.exe python ".\packages\content.example.package\execute_openssl.py .\logs\demo_python" --clean=logs --log-to-file --verbose

# Integration with bootstrapping feature
VirtualClient bootstrap --package=content.example.package.1.0.0.zip --name=content.example.package.1.0.0 --packages="%PACKAGE_STORE%" --clean=packages

VirtualClient.exe pwsh ".\packages\content.example.package.1.0.0\Invoke-OpenSsl.ps1 -LogDirectory .\logs\demo_pwsh" --clean=logs --log-to-file --verbose

# Support for commands
VirtualClient.exe command "pip install -r S:\Demo\content.example.package\setup\requirements.txt" --clean=logs --log-to-file --verbose

[yangpanMS]

I'm thinking if we just do
VirtualClient.exe command "pwsh S:\a.ps1"
instead of a
VirtualClient pwsh "S:\a.ps1"

[brdeyo]

We have confirmation on the changes from the reviewer.