feat: add metrics

[dapplion]

Minimal set of metrics to track errors and measure packet rate

• xxHandshakeSuccesses: Total count of xxHandshake successes
• xxHandshakeErrors: Total count of xxHandshake errors
• encryptedPackets: Total count of successfully encrypted packets
• decryptedPackets: Total count of successfully decrypted packets
• decryptErrors: Total count of errors decrypting packets

[achingbrain]

Can these metrics please get added to the built in libp2p metrics object instead of being their own thing?

[dapplion]

ComponentMetricsUpdate is quite strange, how does this connects to Prometheus? Why is this data structure so nested? A single metric name would be sufficient, since those must never have collisions in Prometheus

The approach of ComponentMetricsUpdate looks more expensive than the simple metric.inc() this PR does. Given that this is done per package can be significant. What's the point of having a "central" place of metrics?

Note gossipsub rolls its own metrics system too https://github.com/ChainSafe/js-libp2p-gossipsub/blob/master/src/metrics.ts

[dapplion]

Updated PR to use a "metrics generator" so that consumer only needs to pass something that can create Gauge instances. This follows similar encapsulation principles as built in libp2p metrics object but with no performance penalty.

[mpetrunic]

superseeded by #246