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/consensus/slots/Cargo.toml

@@ -19,7 +19,6 @@ targets = ["x86_64-unknown-linux-gnu"]
 codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = ["derive", "max-encoded-len"] }
 scale-info = { version = "2.10.0", default-features = false, features = ["derive"] }
 serde = { features = ["alloc", "derive"], optional = true, workspace = true }
-sp-std = { path = "../../std", default-features = false }
 sp-timestamp = { path = "../../timestamp", default-features = false }
 
 [features]
@@ -28,7 +27,6 @@ std = [
 	"codec/std",
 	"scale-info/std",
 	"serde/std",
-	"sp-std/std",
 	"sp-timestamp/std",
 ]