* * Add following to banking_stage:
1. CostModel as immutable ref shared between threads, to provide estimated cost for transactions.
2. CostTracker which is shared between threads, tracks transaction costs for each block.
* replace hard coded program ID with id() calls
* Add Account Access Cost as part of TransactionCost. Account Access cost are weighted differently between read and write, signed and non-signed.
* Establish instruction_execution_cost_table, add function to update or insert instruction cost, unit tested. It is read-only for now; it allows Replay to insert realtime instruction execution costs to the table.
* add test for cost_tracker atomically try_add operation, serves as safety guard for future changes
* check cost against local copy of cost_tracker, return transactions that would exceed limit as unprocessed transaction to be buffered; only apply bank processed transactions cost to tracker;
* bencher to new banking_stage with max cost limit to allow cost model being hit consistently during bench iterations
Tao Zhu