Surface `local_capture_clock_offset` from `RtpSource`

- Propagating `RtpPacketInfo::local_capture_clock_offset`, an
  existing field that is related to the abs-capture-timestamp
  header extension field `estimated_capture_clock_offset`
- Propagated through `SourceTracker::SourceEntry`

Bug: webrtc:10739, b/246753278
Change-Id: I21d9841e4f3a35da5f8d7b31582898309421d524
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275241
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38129}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index e9db503..10337cb 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -94,6 +94,7 @@
     ":rtp_headers",
     ":scoped_refptr",
     "../rtc_base/system:rtc_export",
+    "units:time_delta",
     "units:timestamp",
   ]
   absl_deps = [ "//third_party/abseil-cpp/absl/types:optional" ]