StateDB intermediate state reset when opening DB to force getting always last
Checkpoint at last BatchNum, avoiding inconsistent intermediate state.

* Synchronizer

* mend

Synchronizer main loop & reorg

* mend

Synchronizer main loop & reorg

* mend

Synchronizer main loop & reorg

* Update PR and apply small changes

Update PR and apply small changes:
- Remove arbitrary line jumps (for example after an `err:=` there are cases with extra line before error check, and there are cases without the extra jumpline. Another example is the empty lines between a comment and the line of comment that is explained)
- Fix some typo
- Fix value printing of `lastSavedBlock` instead of `latestBlockNum`
- Uncomment parameters of structs and use linter syntax to avoid unused checks

* Update Synchr after master-pull to last types to compile

Co-authored-by: Toni Ramírez <toni@iden3.com>
Co-authored-by: arnaucube <root@arnaucube.com>

Co-authored-by: Eduard S <eduard@iden3.io>