Drop sc-client (#1037)

* WIP

* collator

* fix missing reference

* Make collator builder more generic

* all clear

* revert start colator fn

* fix return type of start_collator

* sc-consensus

* bump back to master

* Update collator/src/lib.rs

Co-Authored-By: Benjamin Kampmann <[email protected]>

* Update collator/src/lib.rs

Co-Authored-By: Pierre Krieger <[email protected]>

* uncomment type MaxIterations

* reactivate append storage feature

Co-authored-by: Benjamin Kampmann <[email protected]>
Co-authored-by: Pierre Krieger <[email protected]>