Prometheus metrics for RPC calls (#7088)

* WS and HTTP middlewares added

* Prometheus endpoint added

* Counters renamed

* Proper style for inc

* Metrics initialization re-written

* Rework to handler middleware

* Introduce transport prefix for metrics

* String shortened

* Commented code removed, new line inserted

* One more string shortened

* Wasm build fixed

* Wasm build fixed once again

* Rework to shared metrics

* Added collectors label

* Tilde removed from cargo

* Switch to owned metrics in parameters