Update `address_current_token_balances` that are out-of-date

Fixes #1317

Some bug in the past causes `address_current_token_balances` to not
always be up-to-date.  The verifier below show the number of incorrect
`address_current_token_balances` not growing, so the bug itself is
fixed, but the data is still wrong and need to be updated.

Run
`apps/explorer/priv/repo/migrations/scripts/update_address_current_token_balances_in_batches.sql`
to fix any `address_current_token_balances` that have the incorrect
`block_number` or `value`.

Run the following to verify everything is fixed:

```sql
SELECT COUNT(*)
FROM (SELECT 1
FROM address_token_balances
INNER JOIN address_current_token_balances
ON address_current_token_balances.address_hash =
address_token_balances.address_hash AND
   address_current_token_balances.token_contract_address_hash =
address_token_balances.token_contract_address_hash
GROUP BY address_token_balances.address_hash,
         address_token_balances.token_contract_address_hash,
         address_current_token_balances.block_number
HAVING MAX(address_token_balances.block_number) !=
address_current_token_balances.block_number) AS
address_incorrect_token_balances;
```

Which should return `0`. after the script is run.  WARNING: the check
SQL above will take 15-20 minutes on Eth Mainnet.

apps/explorer/priv/repo/migrations/scripts/update_address_current_token_balances_in_batches.sql

@@ -0,0 +1,92 @@
+DO $$
+  DECLARE
+    row_count  integer := 1;
+    batch_size integer := 50000; -- HOW MANY ITEMS WILL BE UPDATED AT TIME
+    iterator   integer := batch_size;
+    affected   integer;
+  BEGIN
+    DROP TABLE IF EXISTS address_token_temp;
+    CREATE TEMP TABLE address_token_temp
+    (
+      address_hash                bytea NOT NULL,
+      token_contract_address_hash bytea NOT NULL,
+      row_number                  integer
+    );
+    INSERT INTO address_token_temp
+    SELECT DISTINCT ON (address_hash, token_contract_address_hash) address_hash,
+                                                                   token_contract_address_hash,
+                                                                   ROW_NUMBER() OVER ()
+    FROM address_token_balances
+    WHERE value IS NOT NULL
+    ORDER BY address_hash, token_contract_address_hash;
+
+    row_count := (SELECT COUNT(*) FROM address_token_temp);
+    RAISE NOTICE '% items to be updated', row_count;
+
+    -- ITERATES THROUGH THE ITEMS UNTIL THE TEMP TABLE IS EMPTY
+    WHILE row_count > 0
+      LOOP
+        UPDATE address_current_token_balances
+        SET block_number = new_address_current_token_balances.block_number,
+            value        = new_address_current_token_balances.value,
+            inserted_at  = new_address_current_token_balances.inserted_at,
+            updated_at   = new_address_current_token_balances.updated_at
+        FROM (
+               SELECT address_token_blocks.address_hash,
+                      address_token_blocks.token_contract_address_hash,
+                      address_token_blocks.block_number,
+                      address_token_balances.value,
+                      MIN(address_token_balances.inserted_at) OVER w AS inserted_at,
+                      MAX(address_token_balances.updated_at) OVER w  AS updated_at
+               FROM (
+                      SELECT address_token_batch.address_hash,
+                             address_token_batch.token_contract_address_hash,
+                             MAX(address_token_balances.block_number) AS block_number
+                      FROM (
+                             SELECT address_hash,
+                                    token_contract_address_hash
+                             FROM address_token_temp
+                             WHERE address_token_temp.row_number <= iterator
+                           ) AS address_token_batch
+                             INNER JOIN address_token_balances
+                                        ON address_token_balances.address_hash = address_token_batch.address_hash AND
+                                           address_token_balances.token_contract_address_hash =
+                                           address_token_batch.token_contract_address_hash
+                      GROUP BY address_token_batch.address_hash,
+                               address_token_batch.token_contract_address_hash
+                    ) AS address_token_blocks
+                      INNER JOIN address_token_balances
+                                 ON address_token_balances.address_hash = address_token_blocks.address_hash AND
+                                    address_token_balances.token_contract_address_hash =
+                                    address_token_blocks.token_contract_address_hash AND
+                                    address_token_balances.block_number = address_token_blocks.block_number
+                    WINDOW w AS (PARTITION BY address_token_balances.address_hash, address_token_balances.token_contract_address_hash)
+             ) AS new_address_current_token_balances
+        WHERE new_address_current_token_balances.address_hash = address_current_token_balances.address_hash
+          AND
+            new_address_current_token_balances.token_contract_address_hash =
+            address_current_token_balances.token_contract_address_hash
+          AND
+          (new_address_current_token_balances.block_number != address_current_token_balances.block_number OR
+           new_address_current_token_balances.value != address_current_token_balances.value);
+
+        GET DIAGNOSTICS affected = ROW_COUNT;
+        RAISE NOTICE '-> % address current token balances updated.', affected;
+
+        DELETE
+        FROM address_token_temp
+        WHERE address_token_temp.row_number <= iterator;
+
+        GET DIAGNOSTICS affected = ROW_COUNT;
+        RAISE NOTICE '-> % address tokens removed from queue.', affected;
+
+        -- COMMITS THE BATCH UPDATES
+        CHECKPOINT;
+
+        -- UPDATES THE COUNTER SO IT DOESN'T TURN INTO AN INFINITE LOOP
+        row_count := (SELECT COUNT(*) FROM address_token_temp);
+        iterator := iterator + batch_size;
+        RAISE NOTICE '-> % counter', row_count;
+        RAISE NOTICE '-> % next batch', iterator;
+      END LOOP;
+  END $$;