Creates a CloudWatch Metric Filter to extract metrics from logs.
 Example:
 metricFilter "ErrorCount" {
     logGroup myLogGroup
     filterPattern (FilterPatterns.errorLogs())
     metricName "ErrorCount"
     metricNamespace "MyApp"
 }

 Creates a CloudWatch Subscription Filter to stream logs to a destination.
 Example:
 subscriptionFilter "LogsToLambda" {
     logGroup myLogGroup
     destination lambdaDestination
     filterPattern (FilterPatterns.allEvents())
 }