Expose platform checks as CMake targets

cmake/PanoPainterAutomation.cmake

@@ -0,0 +1,23 @@
+find_program(PP_POWERSHELL_COMMAND NAMES pwsh powershell)
+
+function(pp_add_powershell_automation_target target_name)
+    cmake_parse_arguments(PP_AUTOMATION_TARGET "" "COMMENT" "ARGUMENTS" ${ARGN})
+
+    if(PP_POWERSHELL_COMMAND)
+        add_custom_target(${target_name}
+            COMMAND "${PP_POWERSHELL_COMMAND}"
+                -NoProfile
+                -ExecutionPolicy Bypass
+                ${PP_AUTOMATION_TARGET_ARGUMENTS}
+            WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+            COMMENT "${PP_AUTOMATION_TARGET_COMMENT}"
+            USES_TERMINAL
+            VERBATIM)
+    else()
+        add_custom_target(${target_name}
+            COMMAND "${CMAKE_COMMAND}" -E echo "PowerShell was not found; cannot run ${target_name}."
+            COMMAND "${CMAKE_COMMAND}" -E false
+            COMMENT "${PP_AUTOMATION_TARGET_COMMENT}"
+            VERBATIM)
+    endif()
+endfunction()