Snapshot sync headers stage (#1836)

* save state

* snapshot update works

* save state

* snapshot migrator

* tx test

* save state

* migrations stages refactor

* refactor snapshot migrator

* compilation fixed

* integrate snapshot migrator

* goerli sync headers

* debug async snapshotter on goerly

* move verify headers, remove experiments, fix remove old snapshot

* save state

* refactor snapshotsync injection

* fix deadlock

* replace snapshot generation stage logic to migrate method

* change done for body snapshot

* clean

* clean&&change deleted value

* clean

* fix hash len

* fix hash len

* remove one of wrap methods, add remove snapshots on start

* add err check

* fix shadowing

* stages unwind order debug

* matryoshka experiments

* steam test

* fix build

* fix test

* fix lint

* fix test

* fix test datarace

* add get test

* return timeout

* fix mdbx overlap

* fix after merge

* change epoch size

* clean todo

* fix

* return testdata

* added return from sndownloader gorutine

* fix review comments

* Fix

* More info

Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro.local>