* Handle negative bigInt in store host API
* Increase size of bigInt in fromString API to support UInt256
* Implement bigDecimal divideBy host API
* Implement bigDecimal plus, minus and times host API
* Implement bigInt dividedByDecimal and mod host API
* Change BN js version to that used by ethers js
* Implement store get api without blockHash and blockNumber
* Pass database instance to GraphWatcher
* Implement store set without block data
* Store blockHash and blockNumber in database entity table
* Implement getting entity in subgraph from store.get
* Add block data present in postgraphile
* Pass db and context to instantiate method in tests
* GQL API in graph-test-watcher to test store.set
* Remove contract address from subgraph file
* Fix block in dummy event data
* Pass just blockHash to get an entity from the database
* Review changes and add TODOs
Co-authored-by: prathamesh <prathamesh.musale0@gmail.com>
* Invoke subgraph handler in watcher event processing
* Fix error when invoking subgraph handler
* Parse events using event signature specified in subgraph yaml
* Use contract abi to parse event params
* Invoke event handler based on event signature
* Fill event with block and transaction data
* Comment missing fields in block and transaction data
