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/metadata-ir/src/lib.rs

@@ -20,6 +20,8 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(missing_docs)]
 
+extern crate alloc;
+
 // Re-export.
 #[doc(hidden)]
 pub use frame_metadata;
@@ -52,8 +54,8 @@ pub fn into_version(metadata: MetadataIR, version: u32) -> Option<RuntimeMetadat
 }
 
 /// Returns the supported metadata versions.
-pub fn supported_versions() -> sp_std::vec::Vec<u32> {
-	sp_std::vec![V14, V15]
+pub fn supported_versions() -> alloc::vec::Vec<u32> {
+	alloc::vec![V14, V15]
 }
 
 /// Transform the IR to the latest stable metadata version.