CMake: Decouple cmake utility functions from top-level CMakeLists.txt

Problem:
- These utility functions are only used in `AK`, but are being defined
  in the top-level. This clutters the top-level.

Solution:
- Move the utility functions to `Meta/CMake/utils.cmake` and include
  where needed.
- Also, move `all_the_debug_macros.cmake` into `Meta/CMake` directory
  to consolidate the location of `*.cmake` script files.

Meta/check-debug-flags.sh

@@ -11,7 +11,7 @@ while IFS= read -r FLAG; do
     # We simply search whether the CMakeLists.txt *ever* sets the flag.
     # There are (basically) no false positives, but there might be false negatives,
     # for example we intentionally don't check for commented-out lines here.
-    if ! grep -qP "add_compile_definitions\(\"${FLAG}" Meta/all_the_debug_macros.cmake ; then
+    if ! grep -qP "add_compile_definitions\(\"${FLAG}" Meta/CMake/all_the_debug_macros.cmake ; then
         echo "ALL_THE_DEBUG_MACROS probably doesn't include ${FLAG}"
         MISSING_FLAGS=y
     fi