Smoke test Windows cmd installer wrapper

.github/workflows/ci.yml

@@ -88,6 +88,21 @@ jobs:
             $errors | ForEach-Object { Write-Error $_ }
             exit 1
           }
+      - name: cmd installer smoke check
+        shell: pwsh
+        run: |
+          $stub = Join-Path $PWD "dosh-install-smoke.ps1"
+          @'
+          param([string]$SmokeArg)
+          if ($SmokeArg -ne "ok") { throw "missing forwarded argument" }
+          $bindir = Join-Path $env:TEMP "dosh-smoke-bin"
+          if ($env:DOSH_INSTALL_BINDIR_FILE) {
+              [System.IO.File]::WriteAllText($env:DOSH_INSTALL_BINDIR_FILE, $bindir, [System.Text.Encoding]::ASCII)
+          }
+          '@ | Set-Content -Encoding ascii -NoNewline $stub
+          $cmd = 'set "DOSH_INSTALL_PS1={0}"&& call install.cmd ok&& echo ;!PATH!; | find /I ";{1}\dosh-smoke-bin;"' -f $stub, $env:TEMP
+          cmd /d /v:on /c $cmd
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
       - name: Build Windows client
         run: cargo build --release --bin dosh-client --bin dosh-bench
       - name: Test Windows client