Apply Scope Modifications To Transactions

[Fwang36]

Currently, any scope configurations such as set_user or set_tag only apply to Error Events for the Rust SDK. We should implement this for transactions as well.

[hobofan]

It looks like this has been partially implemented in #590.

It works for me with set_tag now, but the values for set_user still don't propagate as far as I can tell.