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/externalities/src/extensions.rs

@@ -23,10 +23,12 @@
 //! It is required that each extension implements the [`Extension`] trait.
 
 use crate::Error;
-use sp_std::{
-	any::{Any, TypeId},
+use alloc::{
 	boxed::Box,
 	collections::btree_map::{BTreeMap, Entry},
+};
+use core::{
+	any::{Any, TypeId},
 	ops::DerefMut,
 };