(4) Rename files to snake_case: update BUILD.gn, include paths, header guards, and DEPS entries

Mechanically generated by running this command:

tools_webrtc/do-renames.sh update all-renames.txt && git cl format

Then manually updating:

tools_webrtc/sanitizers/tsan_suppressions_webrtc.cc

Bug: webrtc:10159
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I54824cd91dada8fc3ee3d098f971bc319d477833
Reviewed-on: https://webrtc-review.googlesource.com/c/115653
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26226}

pc/jsep_transport.cc

diff --git a/pc/jsep_transport.cc b/pc/jsep_transport.cc
index 3372f19..fd6bd0d 100644
--- a/pc/jsep_transport.cc
+++ b/pc/jsep_transport.cc
@@ -8,7 +8,7 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "pc/jseptransport.h"
+#include "pc/jsep_transport.h"
 
 #include <stddef.h>
 #include <stdint.h>
@@ -19,10 +19,10 @@
 #include "absl/memory/memory.h"
 #include "api/array_view.h"
 #include "api/candidate.h"
-#include "p2p/base/p2pconstants.h"
-#include "p2p/base/p2ptransportchannel.h"
+#include "p2p/base/p2p_constants.h"
+#include "p2p/base/p2p_transport_channel.h"
 #include "rtc_base/checks.h"
-#include "rtc_base/copyonwritebuffer.h"
+#include "rtc_base/copy_on_write_buffer.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/strings/string_builder.h"