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/statement-store/Cargo.toml

@@ -21,7 +21,6 @@ scale-info = { version = "2.10.0", default-features = false, features = ["derive
 sp-core = { path = "../core", default-features = false }
 sp-crypto-hashing = { path = "../crypto/hashing", default-features = false }
 sp-runtime = { path = "../runtime", default-features = false }
-sp-std = { path = "../std", default-features = false }
 sp-api = { path = "../api", default-features = false }
 sp-application-crypto = { path = "../application-crypto", default-features = false }
 sp-runtime-interface = { path = "../runtime-interface", default-features = false }
@@ -57,7 +56,6 @@ std = [
 	"sp-externalities/std",
 	"sp-runtime-interface/std",
 	"sp-runtime/std",
-	"sp-std/std",
 	"thiserror",
 	"x25519-dalek",
 ]

substrate/primitives/statement-store/src/lib.rs

@@ -20,13 +20,15 @@
 
 //! A crate which contains statement-store primitives.
 
+extern crate alloc;
+
+use alloc::vec::Vec;
 use codec::{Decode, Encode};
 use scale_info::TypeInfo;
 use sp_application_crypto::RuntimeAppPublic;
 #[cfg(feature = "std")]
 use sp_core::Pair;
 use sp_runtime_interface::pass_by::PassByCodec;
-use sp_std::vec::Vec;
 
 /// Statement topic.
 pub type Topic = [u8; 32];

substrate/primitives/statement-store/src/runtime_api.rs

@@ -18,11 +18,11 @@
 //! Runtime support for the statement store.
 
 use crate::{Hash, Statement, Topic};
+use alloc::vec::Vec;
 use codec::{Decode, Encode};
 use scale_info::TypeInfo;
 use sp_runtime::RuntimeDebug;
 use sp_runtime_interface::{pass_by::PassByEnum, runtime_interface};
-use sp_std::vec::Vec;
 
 #[cfg(feature = "std")]
 use sp_externalities::ExternalitiesExt;