On windows, construct environment separately when storing to registry

[sbc100]

We can't use the same set of environment variables when setting local
values and when storing to the windows registry.

This is because the new PATH value is constructed very differently
when updating the local shell compared to when updating the
registry.

Add test that verifies that no path elements are removed by
emsdk_env. This includes not re-ordering or removing duplicates
that might exist already in the user's path.

Fixes: #634

[aminya]

See #642 (comment). That PR considers all the cases (--system, --permamnet, none of them). It includes the tests for all of them.

[aminya]

I am interested to know if this fixes the Process PATH preservation.

You can add process test by pasting this code at here and here

        if (Compare-Object -ReferenceObject $PATH_Process_BEFORE.Split(';') -DifferenceObject $PATH_Process.Split(';') ) {
            echo "Old process path is ...................."
            echo $PATH_Process_BEFORE
            echo "Current process path is ................"
            echo $PATH_Process
            throw "User PATH are changed while --system had been provided"
        }

[sbc100]

I am interested to know if this fixes the Process PATH preservation.

You can add process test by pasting this code at here and here

        if (Compare-Object -ReferenceObject $PATH_Process_BEFORE.Split(';') -DifferenceObject $PATH_Process.Split(';') ) {
            echo "Old process path is ...................."
            echo $PATH_Process_BEFORE
            echo "Current process path is ................"
            echo $PATH_Process
            throw "User PATH are changed while --system had been provided"
        }

I don't think that will work because activation is supposed to add to the process path so it will be different afterwards.

The test that I've added added in this RR in scripts/check_path.py instread checked that all of the element of the original path still appear in the new path and that none were removed. i.e. that the operation only added to the process path and did not remove or re-order the existing process path.