adding transaction listing index

[Chengxuan]

This PR adds 2 indices that helps on transaction listing when the number of transaction rows grows significantly:

• a composite index of from,status and nonce for the transaction handler to fetch unprocessed transactions for a give "from" address
• an index on created for time window based list queries

NOTE: for a DB with a large volume of PENDING transaction records, this new migration could take a long time to run