Implement throttled logger

[swift1337]

We use zerolog's sampled logger for reducing the noise that might be produced with repeated checks/tasks.

node/zetaclient/chains/solana/observer/outbound.go

Line 53 in cfcf706

sampledLogger.Info().Msgf("WatchOutbound: outbound observation is disabled for chain %d", chainID)

I thought that we could introduce some simple wrapper that would implement throttling behaviour

logger := zerolog.New(...)

// creates a new logger wrapper that allows 1 unique log per 5 seconds
tlog := throttlelog.New(5  * time.Second)

var i int
for {
    key := fmt.Sprintf("is_even:%t", i % 2 == 0)
    i++
  
    tlog(key, logger.Info().Str("hello", "world").Int("iteration", i)).Msg("Tick")
     
    time.Sleep(time.Second)
}

// Tick hello=world iteration=0
// Tick hello=world iteration=1
// ... sleep for 5s
// Tick hello=world iteration=10
// Tick hello=world iteration=11
// ...

The possible drawback of this approach is that we need to invoke some mutex & timestamp checker on each invocation and introduce additional allocations. But practically, we use sampled loggers only in edge cases when something is broken or disabled, so it should not hurt the performance but reduce unnecessary logs volume and avoid reimplementing sync.Once-like behavior for logs.