Reject storage proofs with unused nodes: begin (#1878)

* reject storage proofs with unused nodes: begin

* fix ignores_parachain_head_if_it_is_missing_from_storage_proof

* message_proof_is_rejected_if_it_has_duplicate_trie_nodes && message_proof_is_rejected_if_it_has_unused_trie_nodes

* proof_with_duplicate_items_is_rejected and proof_with_unused_items_is_rejected

* clippy

* fix benchmarks compilation

* impl From<Error> for &'static str

* fix review comments

* added comment