Allow passing an event log as string to NetEqSimulator.

Previously only reading from the filesystem was supported, this CL
allows parsing an event log from a string.

Bug: webrtc:10337
Change-Id: Iadde3319eb8fb4175625f510201fac9c01c80ed9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/127296
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Minyue Li <minyue@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27202}

modules/audio_coding/neteq/tools/neteq_rtpplay.cc

@@ -377,8 +377,8 @@ int main(int argc, char* argv[]) {
     config.ssrc_filter = absl::make_optional(ssrc);
   }
 
-  std::unique_ptr<webrtc::test::NetEqTest> test = factory.InitializeTest(
-      /*input_filename=*/argv[1], config);
+  std::unique_ptr<webrtc::test::NetEqTest> test =
+      factory.InitializeTestFromFile(/*input_filename=*/argv[1], config);
   test->Run();
   return 0;
 }