Revert "Delete PeerConnectionInterface::BitrateParameters"

This reverts commit e2dfe74b0e29558ddea6473d0272bc38c838370c.

Reason for revert: Breaks downstream project

Original change's description:
> Delete PeerConnectionInterface::BitrateParameters
> 
> Replaced by the api struct BitrateSettings, added in
> https://webrtc-review.googlesource.com/74020
> 
> Bug: None
> Change-Id: I8b50b32f5c7a8918fad675904d913a21fd905274
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/177665
> Commit-Queue: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Reviewed-by: Taylor <deadbeef@webrtc.org>
> Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#31714}

TBR=deadbeef@webrtc.org,ilnik@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org,kthelgason@webrtc.org

Change-Id: Ia62b3c43996e95668d7972882baf06a186a539d3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: None
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/179221
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31719}
diff --git a/api/peer_connection_interface.h b/api/peer_connection_interface.h
index fd4d2df..2664af4 100644
--- a/api/peer_connection_interface.h
+++ b/api/peer_connection_interface.h
@@ -1015,13 +1015,28 @@
   virtual bool RemoveIceCandidates(
       const std::vector<cricket::Candidate>& candidates) = 0;
 
+  // 0 <= min <= current <= max should hold for set parameters.
+  struct BitrateParameters {
+    BitrateParameters();
+    ~BitrateParameters();
+
+    absl::optional<int> min_bitrate_bps;
+    absl::optional<int> current_bitrate_bps;
+    absl::optional<int> max_bitrate_bps;
+  };
+
   // SetBitrate limits the bandwidth allocated for all RTP streams sent by
   // this PeerConnection. Other limitations might affect these limits and
   // are respected (for example "b=AS" in SDP).
   //
   // Setting |current_bitrate_bps| will reset the current bitrate estimate
   // to the provided value.
-  virtual RTCError SetBitrate(const BitrateSettings& bitrate) = 0;
+  virtual RTCError SetBitrate(const BitrateSettings& bitrate);
+
+  // TODO(nisse): Deprecated - use version above. These two default
+  // implementations require subclasses to implement one or the other
+  // of the methods.
+  virtual RTCError SetBitrate(const BitrateParameters& bitrate_parameters);
 
   // Enable/disable playout of received audio streams. Enabled by default. Note
   // that even if playout is enabled, streams will only be played out if the