* Add support for unauthenticated pprof access on a per-listener basis, as we do for metrics.
* Add missing pprof sub-targets like 'allocs' and 'block'. Capture the goroutine subtarget a second time in text form. This is mostly a convenience, but also I think the pprof format might be a bit lossy?
* sys/pprof: add pprof routes to the system backend
* sys/pprof: add pprof paths to handler with local-only check
* fix trailing slash on pprof index endpoint
* use new no-forward handler on pprof
* go mod tidy
* add pprof external tests
* disallow streaming requests to exceed DefaultMaxRequestDuration
* add max request duration test