L1 Synchronizer optimization

[ARR552]

The objective is parallelized the read of events from L1 nodes and process the information read from L1.
To achieve this change, a go routine is needed to read the events from L1. The results are going to be sent to the processAndStore using a channel. The channel must have a defined length by a configuration parameter to allow us to fine tune the value. The default value could be 50 for instance. If the channel is full the go routine should wait.