Metrics for showing current datetime

[telezhnaya]

Now we have only latest_block_height, which I can sometimes cast to datetime accurate enough in my head 😄 , but it's better just to have the other metrics, with the timestamp.
We can easily show block_timestamp / 1000000000 (it's epoch timestamp in seconds), it perfectly fits into i64, and on grafana side we can cast it to human-readable datetime.

As usual, same for balances project.

[roshaans]

@telezhnaya We can already cast the block_timestamp into human-readable DateTime on Grafana at the moment. What value add would outputting metrics as epoch timestamp in seconds bring?

[telezhnaya]

Looking at grafana, can you say where does genesis indexer run now? Which part of blockchain does it collect