Introduce method to simplify creation of ideal emulated network

Bug: b/239799175
Change-Id: I3b082cdeea7748b2f642a864598916bcadf3ec39
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/269240
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37588}

api/test/network_emulation_manager.h

@@ -197,6 +197,11 @@ class NetworkEmulationManager {
   // Returns a mode in which underlying time controller operates.
   virtual TimeMode time_mode() const = 0;
 
+  // Creates an emulated network node, which represents ideal network with
+  // unlimited capacity, no delay and no packet loss.
+  EmulatedNetworkNode* CreateUnconstrainedEmulatedNode() {
+    return CreateEmulatedNode(BuiltInNetworkBehaviorConfig());
+  }
   // Creates an emulated network node, which represents single network in
   // the emulated network layer. Uses default implementation on network behavior
   // which can be configured with `config`. `random_seed` can be provided to