Pass the Sframe decryption config to the receive media channel

The receiver kept its SframeDecryptionConfig to itself. It now passes
it to its media channel through the new
MediaReceiveChannelInterface::SetSframeDecryptionConfig(), both when the
decryptor is created and when the receiver is attached to a new media
channel. This mirrors how the sender passes its SframeEncryptionConfig.

The voice and video receive channels keep the config in their
SframeReceiveOptions. Passing it on to the receive streams is done in
follow-up CLs.

Bug: webrtc:479862368
Change-Id: I3066d0a32ef09b177b559d1fa6c8bcd9472382d9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/515520
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Kacper Wasniowski <kwasniow@cisco.com>
Cr-Commit-Position: refs/heads/main@{#49261}