(#1392) Update refreshenv to detect when not in cmd shell

[corbob]

Description Of Changes

Update the refreshenv.cmd file to detect if being run from a sub shell and properly report that it doesn't work in that scenario.

Motivation and Context

By default, if you don't have a PowerShell profile when Chocolatey is first installed, you don't get the refreshenv alias from the chocolateyProfile.psm1 PowerShell module. This means if you run refreshenv while in PowerShell it actually runs refreshenv.cmd and fails to refresh the environment.

Testing

1. Build the solution with ./build.bat
2. Install the built files choco upgrade chocolatey -pre -y -s ./code_drop/Packages/Chocolatey
3. Run refreshenv in a PowerShell session
4. Verify output regarding not supported there
5. Import module referenced in output
6. Run refreshenv again
7. Verify it works as expected
8. Run refreshenv from a cmd.exe session
9. Verify output of refreshing variables for cmd.exe

Change Types Made

• Bug fix (non-breaking change)
• Feature / Enhancement (non-breaking change)
• Breaking change (fix or feature that could cause existing functionality to change)
• PowerShell code changes.

Related Issue

Fixes #1392

Change Checklist

• Requires a change to the documentation
• Documentation has been updated
• Tests to cover my changes, have been added
• All new and existing tests passed.
• PowerShell v2 compatibility checked.

[coveralls]

Coverage remained the same at 27.584% when pulling 66baa8f on corbob:update-refreshenv into 44c5283 on chocolatey:develop.

[vexx32]

Looks good to me! 💖