Right now core expose aggregate overlay metrics (exported via the metrics endpoint) and computes per peer metrics (not exposed as metrics).

We should export those as part of the peers endpoint (maybe with a new flag if it's too verbose).

This would allow to get a sense of certain things like number of bytes transferred etc on a per peer basis when debugging.

From a quick look at the code, it looks like many metrics are not computed on a per peer basis (because this information is not useful in the "network survey" context), but should be exposed as part of this work.
For example, getOverlayMetrics().mMessageDrop doesn't have a per peer equivalent.

On that note, we may want to use some template helper of sorts to update both metric types at once instead of manually keeping metrics them in sync with code like

    getOverlayMetrics().mByteRead.Mark(byteCount);
    mPeerMetrics.mByteRead += byteCount;