This allows us to use the `ruma_route` convenience function even when we
need to add our own hacks into the responses, thus making us less
reliant on Ruma.
This change is fully automated, except the `rustfmt.toml` changes and
a few clippy directives to allow specific functions with too many lines
because they are longer now.
It comes with a bunch of new lints (yay!) so I fixed them all so CI will
keep working.
Also apparently something about linking changed because I had to change
the checks for deciding the linker flags for static x86_64 builds to
keep working.