* Add transactions from retracted blocks back to the pool

* Line width

* Reverse retracted

With the *authority-discovery* module an authoritative node makes itself
discoverable and is able to discover other authorities. Once discovered, a node
can directly connect to other authorities instead of multi-hop gossiping
information.

1. **Making itself discoverable**

    1. Retrieve its external addresses

    2. Adds its network peer id to the addresses

    3. Sign the above

    4. Put the signature and the addresses on the libp2p Kademlia DHT

2. **Discovering other authorities**

    1. Retrieve the current set of authorities

    2. Start DHT queries for the ids of the authorities

    3. Validate the signatures of the retrieved key value pairs

    4. Add the retrieved external addresses as ~reserved~ priority nodes to the
       peerset


* node/runtime: Add authority-discovery as session handler

The srml/authority-discovery module implements the OneSessionHandler in
order to keep its authority set in sync. This commit adds the module to
the set of session handlers.

* core/network: Make network worker return Dht events on poll

Instead of network worker implement the Future trait, have it implement
the Stream interface returning Dht events.

For now these events are ignored in build_network_future but will be
used by the core/authority-discovery module in subsequent commits.

* *: Add scaffolding and integration for core/authority-discovery module

* core/authority-discovery: Implement module logic itself

* chain+state RPCs are async now

* wrapped too long lines

* create full/light RPC impls from service

* use ordering

* post-merge fix

* generalize tree_root to remove client.backend dependency

* replace client.backend.blockchain.header with client.header

* move used_state_cache_size into client info

* Create intermediate Setup State. Fixes #1134

* remove client.backend from finality proof

* update node-template

* move memory backend into test helper mode

* move test helper into client

* starting the big refactor, remove unused functions

* apply_finality

* apply_finality

* replacing more .backend from environment with client directly

* remove .backend from grandpa by using traits

* remove .backend from babe

* remove .backend from tests where it is not needed

* remove .backend from tests

* fixing tests

* fixing tests

* fixing more tests

* fixing tests

* fix all forks test

* fix style

* fixing unnecessary allocation

* remove old test.

* fix service docs

* apply suggestion

* minor clean ups

* turns out the test-helper features actually is being used!

* fixing line length.

* fix line length

* minor cleaning

* Apply suggestions from code review

thanks, @Basti

Co-Authored-By: Bastian Köcher <[email protected]>

* address grumbles

* simplify finalize block on client

* move block back into inner function

* Apply suggestions from code review

Co-Authored-By: DemiMarie-parity <[email protected]>

* use as.ref instead of match

* Update core/client/src/backend.rs

Co-Authored-By: DemiMarie-parity <[email protected]>

* Move Service::new to a macro

* Move function calls to macros

* Extract offchain_workers and start_rpc in separate function

In follow-up commits, we want to be able to directly call maintain_transaction_pool, offchain_workers, and start_rpc, without having to implement the Components trait.
This commit is a preliminary step: we extract the code to freestanding functions.

* Introduce an AbstractService trait

* Introduce NewService as an implementation detail of Service

* Implement traits on NewService instead

Instead of implementing AbstractService, Future, and Executor on Service, we implement them on NewService instead.

The implementations of AbstractService, Future, and Executor on Service still exist, but they just wrap to the respective implementations for NewService.

* Move components creation back to macro invocation

Instead of having multiple $build_ parameters passed to the macro, let's group them all into one.

This change is necessary for the follow-up commits, because we are going to call new_impl! only after all the components have already been built.

* Add a $block parameter to new_impl

This makes it possible to be explicit as what the generic parameter of the NewServiceis, without relying on type inference.

* Introduce the ServiceBuilder struct

Introduces a new builder-like ServiceBuilder struct that creates a NewService.

* Macro-ify import_blocks, export_blocks and revert_chain

Similar to the introduction of new_impl!, we extract the actual code into a macro, letting us get rid of the Components and Factory traits

* Add export_blocks, import_blocks and revert_chain methods on ServiceBuilder

Can be used as a replacement for the chain_ops::* methods

* Add run_with_builder

Instead of just run, adds run_with_builder to ParseAndPrepareExport/Import/Revert. This lets you run these operations with a ServiceBuilder instead of a ServiceFactory.

* Transition node and node-template to ServiceBuilder

* Transition transaction-factory to the new service factory

This is technically a breaking change, but the transaction-factory crate is only ever used from within substrate-node, which this commit updates as well.

* Remove old service factory

* Adjust the AbstractService trait to be more usable

We slightly change the trait bounds in order to make all the methods usable.

* Make substrate-service-test compile

* Fix the node-cli tests

* Remove the old API

* Remove the components module

* Fix indentation on chain_ops

* Line widths

* Fix bad line widths commit

* Line widths again 🤦



* Fix the sync test

* Apply suggestions from code review

Co-Authored-By: Gavin Wood <[email protected]>

* Address some concerns

* Remove TelemetryOnConnect

* Remove informant::start

* Update jsonrpc

* Rename factory to builder

* Line widths 😩