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.h

@@ -14,5 +14,5 @@
 #include <AK/StringView.h>
 #include <LibCore/System.h>
 
-ErrorOr<void> spawn_helper_process(StringView process_name, Span<StringView> arguments, Core::System::SearchInPath, Optional<Span<StringView const>> environment = {});
+ErrorOr<void> spawn_helper_process(StringView process_name, ReadonlySpan<StringView> arguments, Core::System::SearchInPath, Optional<ReadonlySpan<StringView>> environment = {});
 ErrorOr<Vector<String>> get_paths_for_helper_process(StringView process_name);