Invoke subgraph handler in watcher event processing (#34)

* 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

packages/graph-test-watcher/environments/local.toml

@@ -19,6 +19,7 @@
     gqlApiEndpoint = "http://127.0.0.1:8082/graphql"
     gqlPostgraphileEndpoint = "http://127.0.0.1:5000/graphql"
     rpcProviderEndpoint = "http://127.0.0.1:8081"
+    blockDelayInMilliSecs = 2000
 
   [upstream.cache]
     name = "requests"