[incremental] add last pending reads info in dumpsys

Example section of dumpsys output:
        lastPendingReads:
          fileId: 03300000000000000000000000000000
          metadataHex: 0330
          blockIndex: 857738
          bootClockTsUs: 166877488

Test: manual
BUG: 162600251
Change-Id: I37b04751c2a11972450ce7e9082116f8047e87df
diff --git a/services/incremental/IncrementalService.h b/services/incremental/IncrementalService.h
index 4c4b8bd..eb69470 100644
--- a/services/incremental/IncrementalService.h
+++ b/services/incremental/IncrementalService.h
@@ -257,6 +257,7 @@
         } mHealthBase = {TimePoint::max(), kMaxBootClockTsUs};
         StorageHealthCheckParams mHealthCheckParams;
         int mStreamStatus = content::pm::IDataLoaderStatusListener::STREAM_HEALTHY;
+        std::vector<incfs::ReadInfo> mLastPendingReads;
     };
     using DataLoaderStubPtr = sp<DataLoaderStub>;