Integrate bandwidth in BeaconChain's network coordinates

The current implementation of the BeaconChain's network coordinates set the bandwidth as default with the value: `A` being a middle value.

We should gather the bandwidth for a specific node in the P2P sampling to be aggregated and integrated in the network patch from the BeaconChain's summary.

The bandwidth can be estimated at a time T, but could also be improved with local view from the connection's module.

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Epic: #155

No files, tests, or concrete entry points are named. Start by locating BeaconChain's network-coordinate summary and the P2P sampling path, then determine how bandwidth is estimated or exposed by the connection module. Done means the sampled bandwidth is aggregated and included in the BeaconChain network patch instead of using the default value.

Written by the indexing model from the issue text.