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/transaction-storage-proof/Cargo.toml

@@ -22,7 +22,6 @@ scale-info = { version = "2.10.0", default-features = false, features = ["derive
 sp-core = { path = "../core", optional = true }
 sp-inherents = { path = "../inherents", default-features = false }
 sp-runtime = { path = "../runtime", default-features = false }
-sp-std = { path = "../std", default-features = false }
 sp-trie = { path = "../trie", optional = true }
 
 [features]
@@ -34,6 +33,5 @@ std = [
 	"sp-core/std",
 	"sp-inherents/std",
 	"sp-runtime/std",
-	"sp-std/std",
 	"sp-trie/std",
 ]

substrate/primitives/transaction-storage-proof/src/lib.rs

@@ -20,8 +20,11 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use sp_std::{prelude::*, result::Result};
+extern crate alloc;
 
+use core::result::Result;
+
+use alloc::vec::Vec;
 use codec::{Decode, Encode};
 use sp_inherents::{InherentData, InherentIdentifier, IsFatalError};
 use sp_runtime::traits::{Block as BlockT, NumberFor};