Forward the Dart logging package to Measure on Flutter

On Flutter, Measure can't collect logs automatically. Dart print output and logs from Dart logging frameworks aren't captured. If your app uses the logging package, forward its records to Measure once during startup. Most other logging packages expose a similar hook:

import 'package:logging/logging.dart';
import 'package:measure_flutter/measure_flutter.dart';

void bootstrapMeasureLogging() {
  Logger.root.onRecord.listen((record) {
    Measure.instance.log(record.message, severity: record.level.measureSeverity);
  });
}

extension on Level {
  LogSeverity get measureSeverity {
    if (this >= Level.SHOUT) return LogSeverity.fatal;
    if (this >= Level.SEVERE) return LogSeverity.error;
    if (this >= Level.WARNING) return LogSeverity.warning;
    if (this >= Level.INFO) return LogSeverity.info;
    return LogSeverity.debug;
  }
}