Refactor key management (#3296)

* Add Call type to extensible transactions.

Cleanup some naming

* Merge Resource and BlockExhausted into just Exhausted

* Fix

* Another fix

* Call

* Some fixes

* Fix srml tests.

* Fix all tests.

* Refactor crypto so each application of it has its own type.

* Introduce new AuthorityProvider API into Aura

This will eventually allow for dynamic determination of authority
keys and avoid having to set them directly on CLI.

* Introduce authority determinator for Babe.

Experiment with modular consensus API.

* Work in progress to introduce KeyTypeId and avoid polluting API
with validator IDs

* Finish up drafting imonline

* Rework offchain workers API.

* Rework API implementation.

* Make it compile for wasm, simplify app_crypto.

* Fix compilation of im-online.

* Fix compilation of im-online.

* Fix more compilation errors.

* Make it compile.

* Fixing tests.

* Rewrite `keystore`

* Fix session tests

* Bring back `TryFrom`'s'

* Fix `srml-grandpa`

* Fix `srml-aura`

* Fix consensus babe

* More fixes

* Make service generate keys from dev_seed

* Build fixes

* Remove offchain tests

* More fixes and cleanups

* Fixes finality grandpa

* Fix `consensus-aura`

* Fix cli

* Fix `node-cli`

* Fix chain_spec builder

* Fix doc tests

* Add authority getter for grandpa.

* Test fix

* Fixes

* Make keystore accessible from the runtime

* Move app crypto to its own crate

* Update `Cargo.lock`

* Make the crypto stuff usable from the runtime

* Adds some runtime crypto tests

* Use last finalized block for grandpa authority

* Fix warning

* Adds `SessionKeys` runtime api

* Remove `FinalityPair` and `ConsensusPair`

* Minor governance tweaks to get it inline with docs.

* Make the governance be up to date with the docs.

* Build fixes.

* Generate the inital session keys

* Failing keystore is a hard error

* Make babe work again

* Fix grandpa

* Fix tests

* Disable `keystore` in consensus critical stuff

* Build fix.

* ImOnline supports multiple authorities at once.

* Update core/application-crypto/src/ed25519.rs

* Merge branch 'master' into gav-in-progress

* Remove unneeded code for now.

* Some `session` testing

* Support querying the public keys

* Cleanup offchain

* Remove warnings

* More cleanup

* Apply suggestions from code review

Co-Authored-By: Benjamin Kampmann <ben.kampmann@googlemail.com>

* More cleanups

* JSONRPC API for setting keys.

Also, rename traits::KeyStore* -> traits::BareCryptoStore*

* Bad merge

* Fix integration tests

* Fix test build

* Test fix

* Fixes

* Warnings

* Another warning

* Bump version.