This cleans up `root.go` a bit, adds tests for middleware HTTP transport
functions, and removes two HTTP requests we always always performed previously
when executing *any* client command.
It should improve CLI performance (especially for users with higher latency).
I also noticed we don't have `goleak` enabled for CLI tests, this commit
adds it, but commented out. The reason being that we're nowhere near
being able to enable it yet.
Co-authored-by: Cian Johnston <cian@coder.com>
