sp-std removal from substrate/primitives (#3274)

This PR removes sp-std crate from substrate/primitives sub-directories.

For now crates that have `pub use` of sp-std or export macros that would
necessitate users of the macros to `extern crate alloc` have been
excluded from this PR.

There should be no breaking changes in this PR.

---------

Co-authored-by: Koute <koute@users.noreply.github.com>

substrate/primitives/consensus/beefy/src/mmr.rs

@@ -26,7 +26,8 @@
 //! but we imagine they will be useful for other chains that either want to bridge with Polkadot
 //! or are completely standalone, but heavily inspired by Polkadot.
 
-use crate::{ecdsa_crypto::AuthorityId, ConsensusLog, MmrRootHash, Vec, BEEFY_ENGINE_ID};
+use crate::{ecdsa_crypto::AuthorityId, ConsensusLog, MmrRootHash, BEEFY_ENGINE_ID};
+use alloc::vec::Vec;
 use codec::{Decode, Encode, MaxEncodedLen};
 use scale_info::TypeInfo;
 use sp_runtime::{
@@ -150,10 +151,11 @@ pub use mmr_root_provider::MmrRootProvider;
 mod mmr_root_provider {
 	use super::*;
 	use crate::{known_payloads, payload::PayloadProvider, Payload};
+	use alloc::sync::Arc;
+	use core::marker::PhantomData;
 	use sp_api::ProvideRuntimeApi;
 	use sp_mmr_primitives::MmrApi;
 	use sp_runtime::traits::NumberFor;
-	use sp_std::{marker::PhantomData, sync::Arc};
 
 	/// A [`crate::Payload`] provider where payload is Merkle Mountain Range root hash.
 	///