subsystem benchmarks: add cpu profiling (#2734)

Ready-to-merge version of
https://github.com/paritytech/polkadot-sdk/pull/2601

- Added optional CPU profiling
- Updated instructions how to set up Prometheus, Pyroscope and Graphana
- Added a flamegraph dashboard
<img width="1470" alt="image"
src="https://github.com/paritytech/polkadot-sdk/assets/27277055/c8f3b33d-3c01-4ec0-ac34-72d52325b6e6">

---------

Co-authored-by: ordian <write@reusable.software>

polkadot/node/subsystem-bench/docker/prometheus/prometheus.yml

@@ -0,0 +1,11 @@
+global:
+  scrape_interval: 5s
+
+scrape_configs:
+  - job_name: "prometheus"
+    static_configs:
+    - targets: ["localhost:9090"]
+  - job_name: "subsystem-bench"
+    scrape_interval: 0s500ms
+    static_configs:
+    - targets: ['host.docker.internal:9999']