Merge branch 'master' into ao-validator-discovery-api

* master:
  Companion for 7155 (WeightInfo for Babe and Grandpa) (#1736)
  Companion PR for #7136 (WeightInfo for Session / Offences) (#1735)
  Bump jsonrpc-core to v15 (#1737)
  Companion PR for #6215 (#1654)
  Companion PR for #7138 (WeightInfo for Scheduler) (#1734)
  Companion PR for Bounties #5715 (#1336)