AK+Everywhere: Turn bool keep_empty to an enum in split* functions

Author: https://github.com/demostanis
Commit: 3e8b5ac920
Pull-request: https://github.com/SerenityOS/serenity/pull/15750
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/davidot
Reviewed-by: https://github.com/linusg ✅

Userland/Utilities/cp.cpp

@@ -39,7 +39,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
             bool values_ok = true;
 
-            StringView { s, strlen(s) }.for_each_split_view(',', false, [&](StringView value) {
+            StringView { s, strlen(s) }.for_each_split_view(',', SplitBehavior::Nothing, [&](StringView value) {
                 if (value == "mode"sv) {
                     preserve |= Core::File::PreserveMode::Permissions;
                 } else if (value == "ownership"sv) {