Add latest_tx_timestamp to the address_balance table

[r4mmer]

Summary

We should add a column latest_tx_timestamp to the address_balance and update it whenever a new tx arrives (with the token for the address in question) or in the case of a re-org.

Motivation

The explorer-service queries for an address tokens ordered by most recent activity, the query made in this PR works very well but can be slow when the address has too many transactions since it requires the MAX(timestamp).
We would have 2 solutions, making an index on the timestamp column of the address_tx_history table or having the latest transaction timestamp "saved" on the address_balance table.

Both solutions can solve the issue but the first one still requires the explorer-service to make a sub-query on the address_tx_history table while the second get the same information in a more straightforward manner.