CMake: Rename serenity_* helper functions/macros to ladybird_*

Author: https://github.com/ayeteadoe
Commit: 25f5936dee
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5249
Reviewed-by: https://github.com/gmta ✅

Tests/LibUnicode/CMakeLists.txt

@@ -9,5 +9,5 @@ set(TEST_SOURCES
 )
 
 foreach(source IN LISTS TEST_SOURCES)
-    serenity_test("${source}" LibUnicode LIBS LibUnicode)
+    ladybird_test("${source}" LibUnicode LIBS LibUnicode)
 endforeach()