FEVM - add tipset CID to block store when importing snapshot

[jennijuju]

To resolve filecoin-project/ref-fvm#1053

we can simply calculate and persist these CIDs on snapshot import. (refer to

lotus/chain/store/store.go

Line 960 in 402173e

func (cs *ChainStore) PersistTipset(ctx context.Context, ts *types.TipSet) error {

on how)

[shrenujbansal]

@jennijuju I tried looking at the ref-fvm issue but not sure I understand. Is this issue referring to the single tipset which is set as the head of the node during a snapshot? Or is it referring to all of the tipsets we download as part of the snapshot?