Obj-C SDK Cleanup

This CL separates the files under sdk/objc into logical directories, replacing
the previous file layout under Framework/.

A long term goal is to have some system set up to generate the files under
sdk/objc/api (the PeerConnection API wrappers) from the C++ code. In the shorter
term the goal is to abstract out shared concepts from these classes in order to
make them as uniform as possible.

The separation into base/, components/, and helpers/ are to differentiate between
the base layer's common protocols, various utilities and the actual platform
specific components.

The old directory layout that resembled a framework's internal layout is not
necessary, since it is generated by the framework target when building it.

Bug: webrtc:9627
Change-Id: Ib084fd83f050ae980649ca99e841f4fb0580bd8f
Reviewed-on: https://webrtc-review.googlesource.com/94142
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24493}
diff --git a/sdk/objc/Framework/Headers/WebRTC/RTCIceCandidate.h b/sdk/objc/Framework/Headers/WebRTC/RTCIceCandidate.h
index fb5064e..dbeea22 100644
--- a/sdk/objc/Framework/Headers/WebRTC/RTCIceCandidate.h
+++ b/sdk/objc/Framework/Headers/WebRTC/RTCIceCandidate.h
@@ -8,42 +8,4 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#import <Foundation/Foundation.h>
-
-#import <WebRTC/RTCMacros.h>
-
-NS_ASSUME_NONNULL_BEGIN
-
-RTC_EXPORT
-@interface RTCIceCandidate : NSObject
-
-/**
- * If present, the identifier of the "media stream identification" for the media
- * component this candidate is associated with.
- */
-@property(nonatomic, readonly, nullable) NSString *sdpMid;
-
-/**
- * The index (starting at zero) of the media description this candidate is
- * associated with in the SDP.
- */
-@property(nonatomic, readonly) int sdpMLineIndex;
-
-/** The SDP string for this candidate. */
-@property(nonatomic, readonly) NSString *sdp;
-
-/** The URL of the ICE server which this candidate is gathered from. */
-@property(nonatomic, readonly, nullable) NSString *serverUrl;
-
-- (instancetype)init NS_UNAVAILABLE;
-
-/**
- * Initialize an RTCIceCandidate from SDP.
- */
-- (instancetype)initWithSdp:(NSString *)sdp
-              sdpMLineIndex:(int)sdpMLineIndex
-                     sdpMid:(nullable NSString *)sdpMid NS_DESIGNATED_INITIALIZER;
-
-@end
-
-NS_ASSUME_NONNULL_END
+#import "api/peerconnection/RTCIceCandidate.h"