URLSearchParams iterator doesn't iterate in the correct order

As a simplified implementation, Go's `net.url` package is used internally which represents query strings as a `map[string][]string` which is useful for representing the information, but doesn't guarantee ordering when iterating.

Start by locating the URLSearchParams implementation that uses Go's net.url package and represents query strings as a map[string][]string. Trace its iterator behavior and add coverage for the required ordering; done means iteration preserves the query parameter order consistently.

Written by the indexing model from the issue text.