Everywhere: Use ReadonlySpan<T> instead of Span<T const>

Author: https://github.com/MacDue
Commit: 63b11030f0
Pull-request: https://github.com/SerenityOS/serenity/pull/17328
Reviewed-by: https://github.com/trflynn89

Ladybird/HelperProcess.cpp

@@ -9,7 +9,7 @@
 #include <AK/String.h>
 #include <QCoreApplication>
 
-ErrorOr<void> spawn_helper_process(StringView process_name, Span<StringView> arguments, Core::System::SearchInPath search_in_path, Optional<Span<StringView const>> environment)
+ErrorOr<void> spawn_helper_process(StringView process_name, ReadonlySpan<StringView> arguments, Core::System::SearchInPath search_in_path, Optional<ReadonlySpan<StringView>> environment)
 {
     auto paths = TRY(get_paths_for_helper_process(process_name));
     VERIFY(!paths.is_empty());