Adds babe rpc support (#4729)

* babe_epochAuthorship
remove test-helpers from sp-keyring, bump spec_version, impl_version

* bump Cargo.lock

* add BabeRPC to node-rpc

* rename to BabeApi, remove err_derive

* pass &ServiceBuilder to with_rpc_extensions callback

* sc-consensus-babe-rpc

* Update client/consensus/babe/src/lib.rs

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Better docs, code style chanegs

Co-Authored-By: André Silva <andre.beat@gmail.com>

* new line at the end of Cargo.toml

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>
Co-authored-by: André Silva <andre.beat@gmail.com>

substrate/client/consensus/babe/src/authorship.rs

@@ -144,7 +144,7 @@ fn claim_secondary_slot(
 /// a primary VRF based slot. If we are not able to claim it, then if we have
 /// secondary slots enabled for the given epoch, we will fallback to trying to
 /// claim a secondary slot.
-pub(super) fn claim_slot(
+pub fn claim_slot(
 	slot_number: SlotNumber,
 	epoch: &Epoch,
 	config: &BabeConfiguration,

substrate/client/consensus/babe/src/lib.rs

@@ -119,7 +119,7 @@ use sp_api::ApiExt;
 
 mod aux_schema;
 mod verification;
-mod authorship;
+pub mod authorship;
 #[cfg(test)]
 mod tests;