Add SyncOracle to network's Service (#1543)

* WIP

* WIP

Forked at: e9164236
Parent branch: origin/rococo-branch

* WIP

Forked at: e9164236
Parent branch: origin/rococo-branch

* Apply suggestions from code review

* Update collator/src/lib.rs

* Update collator/src/lib.rs

* Update network/src/protocol/mod.rs