Refactor/reimplement RTC event log triage alerts.

- Moves AnalyzerConfig and helper functions IsAudioSsrc, IsVideoSsrc, IsRtxSsrc, GetStreamNam and GetLayerName to analyzer_common.h
- Moves log_segments() code to rtc_event_log_parser.h
- Moves TriageAlert/Notification code to a new file with a couple of minor fixes to make it less spammy.

Bug: webrtc:11566
Change-Id: Ib33941d8185f7382fc72ed65768e46015e0320de
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174824
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31318}

logging/rtc_event_log/rtc_event_log_unittest.cc

@@ -739,6 +739,11 @@ void RtcEventLogSession::ReadAndVerifyLog() {
   EXPECT_EQ(first_timestamp_ms_, parsed_log.first_timestamp() / 1000);
   EXPECT_EQ(last_timestamp_ms_, parsed_log.last_timestamp() / 1000);
 
+  ASSERT_EQ(parsed_log.log_segments().size(), 1u);
+  EXPECT_EQ(parsed_log.log_segments()[0].start_time_ms(),
+            start_time_us_ / 1000);
+  EXPECT_EQ(parsed_log.log_segments()[0].stop_time_ms(), stop_time_us_ / 1000);
+
   // Clean up temporary file - can be pretty slow.
   remove(temp_filename_.c_str());
 }