Integrate Grandpa Proof Checker into Substrate Pallet (#375)

* Remove the Substrate primitives crate

The types here were only used in one place, the pallet itself. If other
components start using these types we can considering moving them back
into a standalone crate.

* Start trying to integrate justification module

* Make Substrate blocks configurable in Pallet

* WIP: Try and generalize justification test helpers

* Fix tests which use "real" justifications

* Put common test helpers alongside mock code

* Use common helper for creating headers

* Remove usage of UintAuthorityId

This change favours the use of the Ed25519Keyring authorities
in order to keep things consistent with the tests.

* Add documentation around config trait types

* Make test header, hash, and number types consistent

* Update modules/substrate/src/verifier.rs

Co-authored-by: Svyatoslav Nikolsky <[email protected]>

* Update modules/substrate/src/lib.rs

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

* Update modules/substrate/Cargo.toml

Co-authored-by: Svyatoslav Nikolsky <[email protected]>

* Derive `RuntimeDebug` instead of `Debug`

* Add `Paramter` as a trait constraint on config types

Since we use these types as part of the dispatchable functions
we should explicitly require this.

* Enforce that hasher output matches expected hash type

* Accept headers over indexes when making test justifications

* Check that authority sets are valid

* Make Clippy happy

* Apply correct Clippy fix

* Move justification code into primitives module

* Use new module in verifier code

* Add primitives module for Substrate test helpers

* WIP

* Move justification generation into test_helpers

* Revert commits which move `justification` into primitives

This reverts commit 03a381f0

.

Co-authored-by: Svyatoslav Nikolsky <[email protected]>
Co-authored-by: Tomasz Drwięga <[email protected]>