Consensus utilities and rearchitecture for more dynamic collators (#2382)

* implement a proposer utility for consensus

* tidy up deps of new proposer crate

* implement a collator-service crate

* rewrite cumulus-collator to use new service struct

* implement a module for relay-chain-driven collators

* adapt start_collator to use the new relay_chain_driven module

* move collator-service to a public submodule

* create an interface trait for the proposer

* begin aura reimplementation

* address review comments

* update substrrate git ref

* update polkadot-primitives refs

* rough draft of aura collation using standalone fns

* add a ServiceInterface

* port aura reimpl to use new service trait

* add an import queue utility crate

* remove import queue crate in favor of module in common

* implement new verification queue for aura

* implement remaining behaviors

* split 'collate' into smaller functions that could be pub

* add telemetry

* fix doc job?

* Specify async-trait patch version

Co-authored-by: Bastian Köcher <[email protected]>

* remove 'fn@' in doc string.

Co-authored-by: Bastian Köcher <[email protected]>

* update variable names to be more readable

* refactor proposer errors to anyhow/thiserror

* remove manual span instrumentation

Co-authored-by: Bastian Köcher <[email protected]>

* make slot_claim private

* fix unused import

* fmt

* fmt

* make clippy happy

---------

Co-authored-by: Bastian Köcher <[email protected]>