Hashing proc macro utils (#9875)

* hashing macro

* fmt

* use in easy place, and fix blake sizes

* fix

* Fixes, docs.
Allow ident as input.

* fix doc tests

* update error in test (nmapkey and key are same type).

* hashing crates under sp_core

* Doc updates and format.

* use all existing hashing functions.

* return array of u8

* Update primitives/core/hashing/proc-macro/src/impls.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* ToTokeen for an array of u8

* fix

* re

* Improve impls

* complete doc tests

* fmt

* fix doctest format

* fix ui test (nmap key type alias)

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Bastian Köcher <info@kchr.de>

substrate/primitives/core/hashing/proc-macro/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "sp-core-hashing-proc-macro"
+version = "4.0.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "Apache-2.0"
+homepage = "https://substrate.dev"
+repository = "https://github.com/paritytech/substrate/"
+description = "This crate provides procedural macros for calculating static hash."
+documentation = "https://docs.rs/sp-core-hashing-proc-macro"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "1.0.77", features = ["full", "parsing"] }
+quote = "1.0.6"
+proc-macro2 = "1.0.29"
+sp-core-hashing = { version = "4.0.0-dev", path = "../", default-features = false }