Get rid of the `ctry!` & `cexpect!` macros

[jyn514]

Pretty sure we can literally just replace ctry! with ? now given that errors without an explicit status code are treated as 500s (or if we can't, could try and make it so that we can). That would allow changing cexpect! usage into .ok_or_else(|| err_msg(...))?.

Originally posted by @Kixiron and @Nemo157 in #858 (comment)

[Nemo157]

Ok, I just attempted this, and it's not trivial at the moment. IronError doesn't implement From to allow using ? with it since it smushes together application level HTTP error codes and underlying server errors into the same type. This should be doable after/as part of the transition to hyper as long as we don't make the same mistake with the design of our "Handler".

[jyn514]

An easy way to make this nicer is impl From<Nope> for IronError - it will still need map_err in a few places, but fewer of them and shorter. (found in #1045)

[syphar]

both macros are gone after the axum migration was finished.