* Stop passing raw encoded justifications to pallet API

By having the API accept a struct-ified justification we are able to
better utilize the justifications fields for weight calculations.

* Update relayer code to use decoded justifications

* Add justification to `expect()` statement

* Fix some imports

* Make justification wrapper contain decoded justification

* Rename some fields

* Get rid of warnings

* Appease Clippy

* Only decode justification once at init time

* Remove unnecessary method

* Remove justification wrapper

This became kinda unnecessary since we could implement the FinalityProof
trait on GrandpaJustification directly.

* Allow creation of authority lists with any number of authorities

* Move keyring helpers into their own module

* Add helper for generating list of test accounts

* Fix import names in tests

* Rename Keyring trait to Signer

* Get list of accounts in a more functional way

* Clarify meaning of `test_keyring` return type

* Use concrete test account type instead of generics

* Make sure voter set contains all authorities which signed off on pre-commits

* Rename `pallet-finality-verifier` to `pallet-bridge-grandpa`

* Missed some CamelCase ones

* Update logging target in GRANDPA pallet

* Rename `pallet-bridge-call-dispatch` to `pallet-bridge-dispatch`

* Rename the dispatch pallet folder

* Update logging target in Dispatch pallet

* Missed a couple

* Format the repo

* Stop listing individual pallets in Compose logs

* Use correct pallet name in module doc comments

* Add `pallet-bridge-dispatch` to README project layout

* Sort crate names in TOML files

* Rename `pallet-bridge-grandpa` runtime Call alias