Add Github Actions for Windows (#24504)

Setup Installer CI (#25184), (#25191)

Co-authored-by: Zack Galbreath <zack.galbreath@kitware.com>
Co-authored-by: lou.lawrence@kitware.com <lou.lawrence@kitware.com>
Co-authored-by: Betsy McPhail <betsy.mcphail@kitware.com>

bin/spack.bat

@@ -187,7 +187,7 @@ python "%spack%" %_sp_flags% %_sp_subcommand% %_sp_args%
 goto :end_switch
 
 :end_switch
-exit /B 0
+exit /B %ERRORLEVEL%
 
 
 ::########################################################################
@@ -220,4 +220,4 @@ for %%I in (%~2) do (
         :pathadd "%~1" "%%I\%%Z"
     )
 )
-exit /B 0
+exit /B %ERRORLEVEL%

bin/spack_cmd.bat

@@ -14,8 +14,9 @@ popd
 
 
 :: Check if Python is on the PATH
+if not defined python_pf_ver (
 (for /f "delims=" %%F in ('where python.exe') do (set python_pf_ver=%%F) ) 2> NUL
-
+)
 if not defined python_pf_ver (
     :: If not, look for Python from the Spack installer
     :get_builtin
@@ -58,4 +59,9 @@ DOSKEY spacktivate=spack env activate $*
 @echo ** Spack Package Manager
 @echo **********************************************************************
 
+IF "%1"=="" GOTO CONTINUE
+set
+GOTO:EOF
+
+:continue
 %comspec% /k