Additional Metrics collected and exposed via prometheus (#5414)

This PR refactors the metrics measuring and Prometheus exposing entity in sc-service into its own submodule and extends the parameters it exposes by:

- system load average (over one, five and 15min)
- the TCP connection state of the process (lsof), refs #5304
- number of tokio threads
- number of known forks
- counter for items in each unbounded queue (with internal unbounded channels)
- number of file descriptors opened by this process (*nix only at this point)
- number of system threads (*nix only at this point)

refs #4679

Co-authored-by: Max Inden <mail@max-inden.de>
Co-authored-by: Ashley <ashley.ruglys@gmail.com>

substrate/primitives/utils/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "sp-utils"
+version = "2.0.0-alpha.5"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "GPL-3.0"
+homepage = "https://substrate.dev"
+repository = "https://github.com/paritytech/substrate/"
+description = "I/O for Substrate runtimes"
+
+[dependencies]
+futures = "0.3.4"
+futures-core = "0.3.4"
+lazy_static = "1.4.0"
+prometheus = "0.8.0"
+
+[features]
+default = ["metered"]
+metered = []