Replace some SecretSync with a sync implementation

The idea behind SecretSync is a nice thing: it allows use to re-use our async implementations of methods for the synchronous versions. The big problem with it, is that it makes debugging issues much harder (especially with issues related to freezes) since things can seem to be stuck in poll() somewhere.

Even though it adds quite a bit of code, I think it makes sense to replace some instances with a proper synchronous implementation. Note that we don't do this for all usages of SecretSync though, as some things will need some kind of main loop interaction anyway (for example, when waiting for a portal's Response signal)

Another nice advantage is that it's easier to follow the logic in the sync code than the async version.