Data Channel Benchmarking tool

Create a server using:
./data_channel_benchmark --server --port 12345
Start the flow of data from the server to a client using:
./data_channel_benchmark --port 12345 --transfer_size 100
The throughput is reported on the server console.

The negotiation does not require a 3rd party server and is done over a
gRPC transport. No TURN server is configured, so both peers need to be
reachable using STUN only.

Bug: webrtc:13288
Change-Id: Iac9a96cf390ab465ea45a46bf0b40950c56dfceb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235661
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36206}

DEPS

diff --git a/DEPS b/DEPS
index dc31e4d..99fb48d 100644
--- a/DEPS
+++ b/DEPS
@@ -156,6 +156,9 @@
     'url': 'https://chromium.googlesource.com/chromium/deps/findbugs.git@4275d9ac8610db6b1bc9a5e887f97e41b33fac67',
     'condition': 'checkout_android',
   },
+  'src/third_party/grpc/src': {
+    'url': 'https://chromium.googlesource.com/external/github.com/grpc/grpc.git@f8a909e76fcd947949502832a7ab8e2cba2b8e27',
+  },
   # Used for embedded builds. CrOS & Linux use the system version.
   'src/third_party/fontconfig/src': {
       'url': 'https://chromium.googlesource.com/external/fontconfig.git@452be8125f0e2a18a7dfef469e05d19374d36307',