Add switch/feature to validate scripts as posh v2

[AdmiringWorm]

What You Are Seeing?

Even if a install or uninstall script uses function that isn't available in posh v2 choco still treats it as
a valid script.

What is Expected?

Either an error or a warning that the install/uninstall script may not run for posh v2 users,
either automatically when running choco pack or with an extra switch

[ferventcoder]

Thanks!