* Accept finalised hash from RPC with the canon header as well
* Reorg internal sync descriptor(s)
details:
Update target from RPC to provide the `consensus header` as well as
the `finalised` block number
why:
Prepare for using `importBlock()` instead of `persistBlocks()`
* Cosmetic updates
details:
+ Collect all pretty printers in `helpers.nim`
+ Remove unused return codes from function prototype
* Use `importBlock()` + `forkChoice()` rather than `persistBlocks()`
* Update logging and metrics
* Update docu