Keystore overhaul (#13615)

* Remove 'supported_keys' 'sign_with_any' and 'sign_with_all' from keystore trait

* Remove the aync keystore

* Renaming:
- SyncCryptoStore -> Keystore
- SyncCryptoStorePtr -> KeystorePtr
- KeyStore -> MemoryKeystore

* Fix authority discovery worker and tests

* Rename 'insert_unknown' to 'insert'

* Remove leftover

substrate/client/rpc-api/src/author/error.rs

@@ -47,7 +47,7 @@ pub enum Error {
 	BadKeyType,
 	/// Some random issue with the key store. Shouldn't happen.
 	#[error("The key store is unavailable")]
-	KeyStoreUnavailable,
+	KeystoreUnavailable,
 	/// Invalid session keys encoding.
 	#[error("Session keys are not encoded correctly")]
 	InvalidSessionKeys,