[ci] Add -D warnings for cargo-check-each-crate job to fail on warnings (#2670)

## Summary

This PR turns on `-D warnings` for `cargo-check-each-crate job` job to
fail on warnings e.g. like this:
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673130

Before this PR, there was a warning and `cargo-check-each-crate` job did
not fail:
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4641444
```
warning: unused import: `ToTokens`
  --> substrate/primitives/api/proc-macro/src/utils.rs:22:34
   |
22 | use quote::{format_ident, quote, ToTokens};
   |                                  ^^^^^^^^
   |
   = note: `#[warn(unused_imports)]` on by default
warning: `sp-api-proc-macro` (lib) generated 1 warning (run `cargo fix --lib -p sp-api-proc-macro` to apply 1 suggestion)
```

Fixes on the way:
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4641444
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673265
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673410
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673681
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673836
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4673941
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4674256
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4679328



## Questions
- [ ] why does this check triggers only `cargo check --locked`?
`--all-features` or `--all-targets` are not needed? Or aren't they
avoided intentionally?

---------

Co-authored-by: command-bot <>

substrate/primitives/api/proc-macro/src/utils.rs

@@ -19,7 +19,7 @@ use crate::common::API_VERSION_ATTRIBUTE;
 use inflector::Inflector;
 use proc_macro2::{Span, TokenStream};
 use proc_macro_crate::{crate_name, FoundCrate};
-use quote::{format_ident, quote, ToTokens};
+use quote::{format_ident, quote};
 use syn::{
 	parse_quote, spanned::Spanned, token::And, Attribute, Error, FnArg, GenericArgument, Ident,
 	ImplItem, ItemImpl, Pat, Path, PathArguments, Result, ReturnType, Signature, Type, TypePath,
@@ -261,6 +261,7 @@ pub fn versioned_trait_name(trait_ident: &Ident, version: u64) -> Ident {
 /// Extract the documentation from the provided attributes.
 #[cfg(feature = "frame-metadata")]
 pub fn get_doc_literals(attrs: &[syn::Attribute]) -> Vec<syn::Lit> {
+	use quote::ToTokens;
 	attrs
 		.iter()
 		.filter_map(|attr| {