cmake: improve curl_dumpvars() and move to Utilities.cmake

Also:
- dump variable types.
- show which variables are marked as advanced.
- use `IN ITEMS`.

Closes #15562

CMake/Utilities.cmake

@@ -33,3 +33,21 @@ function(count_true _output_count_var)
   endforeach()
   set(${_output_count_var} ${lst_len} PARENT_SCOPE)
 endfunction()
+
+# Dump all defined variables with their values
+function(curl_dumpvars)
+  message("::group::CMake Variable Dump")
+  get_cmake_property(_vars VARIABLES)
+  foreach(_var IN ITEMS ${_vars})
+    get_property(_var_type CACHE ${_var} PROPERTY TYPE)
+    get_property(_var_advanced CACHE ${_var} PROPERTY ADVANCED)
+    if(_var_type)
+      set(_var_type ":${_var_type}")
+    endif()
+    if(_var_advanced)
+      set(_var_advanced " [adv]")
+    endif()
+    message("${_var}${_var_type}${_var_advanced} = ${${_var}}")
+  endforeach()
+  message("::endgroup::")
+endfunction()