* 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.

* Start generalizing rialto-millau commands.

* cargo fmt --all

* Introduce generic balance.

* Unify message payloads.

* cargo fmt --all

* init - generic

* Attempt to unify send message.

* Start moving things around.

* cargo fmt --all

* Move init-bridge.

* cargo fmt --all

* Improve UX of bridge argument.

* Fix clippy.

* Fix docs and scripts.

* Add docs.

* Apply suggestions from code review

Co-authored-by: Hernando Castano <[email protected]>

* Fix copyright.

* Add issue numbers.

* More todos.

* Update comments.

Co-authored-by: Hernando Castano <[email protected]>

* on-demand headers relay

* bool::then

* move file

* atomic submit_signed_extrinsic

* remove cli options from future

* test on-demand relay

* TODOs

* fixed initialization call for Westend -> Millau

* Update relays/client-substrate/src/client.rs

Co-authored-by: Hernando Castano <[email protected]>

* removed on_demand_headers_relay.rs

* on_demand_headers_relay traces

* fix compilation

* fmt

* docs

Co-authored-by: Hernando Castano <[email protected]>

* Remove chains.

* Move relay clients.

* Flatten generic.

* Fix fmt.