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/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;