frame: GenesisBuild::build allowed in no_std (#14107)

* frame: GenesisBuild::build allowed in no_std

i`GenesisBuild::build` function will be required for no_std in no native
runtime world.

`GenesisBuild::build` macro generated function allows to build the runtime
GenesisConfig assembled from all pallets' GenesisConfigs.

* fixes

* GenesisBuild::build avaiable in no-std

- #[cfg(feature = "std")] is not longer added to GenesisBuild implementation.

* system: hash69 available for no-std

* elections-phragmen: panic message fixed for no_std

* frame::suport: doc updated

* test-runtime: default for GenesisConfig

* frame::test-pallet: serde/std added to std feature deps

* Cargo.toml: deps sorted

* Cargo.lock update

cargo update -p frame-support-test-pallet -p frame-support-test

* frame ui tests: cleanup

---------

Co-authored-by: parity-processbot <>

substrate/test-utils/runtime/src/substrate_test_pallet.rs

@@ -55,7 +55,7 @@ pub mod pallet {
 	pub type Authorities<T> = StorageValue<_, Vec<Public>, ValueQuery>;
 
 	#[pallet::genesis_config]
-	#[cfg_attr(feature = "std", derive(Default))]
+	#[derive(Default)]
 	pub struct GenesisConfig {
 		pub authorities: Vec<Public>,
 	}