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/dd.cpp

@@ -38,7 +38,7 @@ enum Status {
 
 static StringView split_at_equals(StringView argument)
 {
-    auto values = argument.split_view('=', true);
+    auto values = argument.split_view('=', SplitBehavior::KeepEmpty);
     if (values.size() < 2) {
         warnln("Unable to parse: {}", argument);
         return {};