Check for misplaced configs on build (#20599)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

buildroot/share/PlatformIO/scripts/common-dependencies.py

@@ -300,6 +300,16 @@ def MarlinFeatureIsEnabled(env, feature):
 
 	return some_on
 
+#
+# Check for Configfiles in two common incorrect places
+#
+def check_configfile_locations():
+	for p in [ env['PROJECT_DIR'], os.path.join(env['PROJECT_DIR'], "config") ]:
+		for f in [ "Configuration.h", "Configuration_adv.h" ]:
+			if os.path.isfile(os.path.join(p, f)):
+				err = 'ERROR: Config files found in directory ' + str(p) + '. Please move them into the Marlin subdirectory.'
+				raise SystemExit(err)
+
 #
 # Add a method for other PIO scripts to query enabled features
 #
@@ -308,5 +318,6 @@ env.AddMethod(MarlinFeatureIsEnabled)
 #
 # Add dependencies for enabled Marlin features
 #
+check_configfile_locations() 
 apply_features_config()
 force_ignore_unused_libs()