Clippyfy (#6341)

* Add clippy config and remove .cargo from gitignore

* first fixes

* Clippyfied

* Add clippy CI job

* comment out rusty-cachier

* minor

* fix ci

* remove DAG from check-dependent-project

* add DAG to clippy

Co-authored-by: alvicsam <alvicsam@gmail.com>

polkadot/scripts/ci/gitlab/pipeline/test.yml

@@ -72,3 +72,18 @@ test-deterministic-wasm:
     - .compiler-info
   script:
     - ./scripts/ci/gitlab/test_deterministic_wasm.sh
+
+cargo-clippy:
+  stage:                           test
+  # this is an artificial job dependency, for pipeline optimization using GitLab's DAGs
+  # the job can be found in check.yml
+  needs:
+    - job:                         job-starter
+      artifacts:                   false
+  variables:
+    RUSTY_CACHIER_TOOLCHAIN: nightly
+  extends:
+    - .docker-env
+    - .test-refs
+  script:
+    - SKIP_WASM_BUILD=1 env -u RUSTFLAGS cargo +nightly clippy --all-targets