Uses the new Ethereum RPC interface to do so

This can be used to implement higher level requests like fetching Substrate headers
from an Ethereum node.

Still missing proper error handling, as well as decoding responses from the
Substrate node.

Does not include RPCs that require the bridge contract.

* solidity contract

* continue

* upd

* cargo update

* fixes

* ehtereum_headers -> headers

* extracted some common stuff

* ethereum_sync.rs -> sync.rs

* make sync generic

* continue extracting

* continue

* add eth-contract argument

* continue

* some fixes

* contract v2

* continue

* more fixes

* more fixes

* deal with duplicated params

* removed multiple call_rpc variants

* bail_on_error!()

* fn submit_ethereum_transaction

* more fixes

* cargo fmt --all

* fix

* bail_on_arg_error!()

* fix

* fix

* remove async_extra stuff

* substrate-bridge.json -> substrate-bridge-abi.json

* get rid of substrate transactions hashes

* get rid of ethereum transactions hashes

* extracted contract bytecode to separate file

* cargo fmt --all

* avoid duplicate import in contracts

* removed Default::default()

* swapped configurations for sub2eth && eth2sub

* fix compilation

* do not double gas limit when submitting Substrate headers

* cargo fmt --all

* solidity contract removed

* consts

* extracted solc compilation details to separate file

* removed (obsolete in future Vec<u8> justification)

* fixed cli option description

* fix typos

* fix grumble

* extracted constants

* log decoded header

* cargo fmt --all

* comment

* new substrate version + actually verify justification

* cargo update + fix remaining stuff

* add weight=0 comments

* cargo fmt --all

* fix hash types

* renamed to-be-generic files

* make everything required generic over source/target chains

* some more fixes

* cargo fmt --all

* trait functions -> trait constants

* cargo --fmt --all

* reward submitters on finalization

* PoA -> Substrate: unsigned_import_header API

* fix grumble

* make submitter part of ImportContext

* verify using next validators set + tests

* fix nostd compilation

* add sub-tx-mode argument

* support sub-tx-mode

* impl ValidateUnsigned for Runtime

* do not submit too much transactions to the pool

* cargo fmt

* fix bad merge

* revert license fix

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Hernando Castano <[email protected]>

* Update modules/ethereum/src/verification.rs

Co-Authored-By: Hernando Castano <[email protected]>

* updated comment

* validate receipts before accepting unsigned tx to pool

* cargo fmt

* fix comment

* fix grumbles

* Update modules/ethereum/src/verification.rs

Co-Authored-By: Hernando Castano <[email protected]>

* cargo fmt --all

* struct ChangeToEnact

* updated doc

* fix doc

* add docs to the code method

* simplify fn ancestry

* finish incomplete docs

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* return err from unsigned_import_header

* get header once

* Update relays/ethereum/src/ethereum_sync.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* fix

* UnsignedTooFarInTheFuture -> Custom(err.code())

* updated ImportContext::last_signal_block

* cargo fmt --all

* rename runtime calls

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

* add missing RPC required for relay

* cargo fmt --all

* Bump time from 0.1.42 to 0.2.9

Bumps [time](https://github.com/time-rs/time) from 0.1.42 to 0.2.9.
- [Release notes](https://github.com/time-rs/time/releases)
- [Changelog](https://github.com/time-rs/time/blob/master/CHANGELOG.md)
- [Commits](https://github.com/time-rs/time/commits/v0.2.9)

Signed-off-by: dependabot-preview[bot] <[email protected]>

* Update to new API.

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Tomasz Drwięga <[email protected]>

* Run RustFmt as part of the CI

* Format repo

* Run RustFmt before the default Travis build step

Apparently if you override `script` you also need to make
sure to `build` and `test` the code yourself.

* Format repo

* reward submitters on finalization

* fix grumble

* make submitter part of ImportContext