Reset watcher to previous indexed block on start (#207)

* Reset watcher to previous indexed block before start

* Implement changes in other watchers

* Save successfully fetched blocks and events to prefetch cache

* Add unique query for transaction table

* Check db for blocks before fetching from eth-server

* Show all mismatches at a block

Co-authored-by: prathamesh0 <prathamesh.musale0@gmail.com>

packages/graph-node/test/utils/indexer.ts

@@ -197,6 +197,10 @@ export class Indexer implements IndexerInterface {
   updateStateStatusMap (address: string, stateStatus: StateStatus): void {
     return undefined;
   }
+
+  async resetWatcherToBlock (blockNumber: number): Promise<void> {
+    return undefined;
+  }
 }
 
 class ServerConfig implements ServerConfigInterface {