Make routes for different endpoints configurable (including switching them off)

[beorn7]

The dev-summit decided (almost a year ago, on 2023-11-30) that we want this.

There was some discussion if this should be only about switching on and off certain endpoints (e.g. /pprof) or do more stuff like binding different endpoints to different ports or interfaces.

/cc @SuperQ @bwplotka

One trigger was prometheus/pushgateway#520 , which has some relevant discussion. But there are regular concerns reported about certain endpoints exposed to the public internet (in particular /pprof and /metrics, but also certain APIs depending on the binary in question). While we do not plan to lockdown binaries by default (cf. dev-summit on 2024-10-24), it would be good to give users an easy way to configure what to expose where.