fix: environment handling windows (host mode) (#1732)

* fix: environment handling windows (host mode)

* fixup

* fixup

* add more tests

* fixup

* fix setenv

* fixes

* [skip ci] Apply suggestions from code review

Co-authored-by: Jason Song <i@wolfogre.com>

* Update side effects

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/runner/testdata/windows-prepend-path/push.yml

@@ -11,6 +11,9 @@ jobs:
         mkdir build
         echo '@echo off' > build/test.cmd
         echo 'echo Hi' >> build/test.cmd
+        mkdir build2
+        echo '@echo off' > build2/test2.cmd
+        echo 'echo test2' >> build2/test2.cmd
     - run: |
         echo '${{ tojson(runner) }}'
         ls
@@ -23,3 +26,9 @@ jobs:
     - run: |
         echo $env:PATH
         test
+    - run: |
+        echo "PATH=$env:PATH;${{ github.workspace }}\build2" > $env:GITHUB_ENV
+    - run: |
+        echo $env:PATH
+        test
+        test2