- In exit table, `instant_withdrawn`, `delayed_withdraw_request`, and
`delayed_withdrawn` were referencing batch_num. But these actions happen
outside a batch, so they should reference a block_num.
- Process delayed withdrawns:
- In Synchronizer, first match a Rollup delayed withdrawn request, with the
WDelayer deposit (via TxHash), and store the owner and token associated
with the delayed withdrawn.
- In HistoryDB: store the owner and token of a delayed withdrawal request
in the exit_tree, and set delayed_withdrawn when the withdraw is done in
the WDelayer.
- Update dependency of sqlx to master
- Last release of sqlx is from 2018 October, and it doesn't support
`NamedQuery` with a slice of structs, which is used in this commit.