This commit adds ability to print metrics of the Tokio
runtime to the console by passing "DENO_TOKIO_METRICS=1"
env var.
Metrics will be printed every second, but this can be changed
by "DENO_TOKIO_METRICS_INTERVAL=500" env var.
Stop allowing clippy::derive-partial-eq-without-eq and fix warnings
about deriving PartialEq without also deriving Eq.
In one case I removed the PartialEq because it a) wasn't necessary,
and b) sketchy because it was comparing floating point numbers.
IMO, that's a good argument for enforcing the lint rule, because it
would most likely have been caught during review if it had been enabled.