Deprecate PeerConnectionFactory::CreatePeerConnection

Applications should use CreatePeerConnectionOrError instead.

Moved fallback implementations of CreatePeerConnection into the
api/peer_connection_interface.h file, so that we do not have to
declare these methods in the proxy.

Bug: webrtc:12238
Change-Id: I70c56336641c2a108b68446ae41f43409277a584
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/217762
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33964}

api/DEPS

diff --git a/api/DEPS b/api/DEPS
index 2e46029..1d3d43f 100644
--- a/api/DEPS
+++ b/api/DEPS
@@ -128,13 +128,18 @@
   "peer_connection_interface\.h": [
     "+media/base/media_config.h",
     "+media/base/media_engine.h",
+    "+p2p/base/port.h",
     "+p2p/base/port_allocator.h",
+    "+rtc_base/network.h",
+    "+rtc_base/network_constants.h",
     "+rtc_base/network_monitor_factory.h",
+    "+rtc_base/ref_count.h",
     "+rtc_base/rtc_certificate.h",
     "+rtc_base/rtc_certificate_generator.h",
     "+rtc_base/socket_address.h",
     "+rtc_base/ssl_certificate.h",
     "+rtc_base/ssl_stream_adapter.h",
+    "+rtc_base/thread.h",
   ],
 
   "proxy\.h": [