Refactor Self-Monitor Directory Structure, Filenames, and Class Names

[Takuka0311]

不涉及逻辑改动

• 目录
  • 移动：
    • core/profile_sender -> core/monitor/profile_sender（Todo：EnterpriseProfileSender需要在内部移一下）
• 文件
  • 新增：
    • core/monitor/MetricRecord.h，把MetricsRecord、MetricsRecordRef移到了这里
  • 更名：
    • core/monitor/LoongCollectorMetricTypes.h -> MetricTypes.h
    • core/monitor/LogtailMetric.h -> MetricManager.h
    • core/monitor/LogtailAlarm.h-> AlarmManager.h
    • core/unittest/monitor/LogtailMetricUnittest.cpp -> MetricManagerUnittest.cpp
• 类
  • 移动
    • ReentrantMetricsRecord、ReentrantMetricsRecordRef移动到了PluginMetricManager.h
  • 更名
    • ILogtailMetricUnittest - > MetricManagerUnittest
    • LogtailAlarmType -> AlarmType
    • LogtailAlarmMessage -> AlarmMessage
    • LogtailAlarm -> AlarmManager
    • LogtailAlarmVector -> AlarmVector