Revert "Remove code supporting the SDES crypto mode in SDP"

This reverts commit ee212a72f220641f0a4a23fb2c1bd600a9069440.

Reason for revert: Don't remove until downstream issues resolved

Original change's description:
> Remove code supporting the SDES crypto mode in SDP
>
> Removes the ability to accept nonencrypted answers to encrypted offers.
> Fixes some logic around bundled sessions and requirement for
> transport parameters.
>
> Bug: webrtc:11066
> Change-Id: I56d8628d223614918a1e5260fdb8a117c8c02dbd
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/236344
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35298}

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: webrtc:11066
Change-Id: I0c400ceffe1b08e0be7b44abbb54c8a032128f05
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/237223
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35312}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index 214600e..0352f99 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -133,6 +133,7 @@
   sources = [
     "candidate.cc",
     "candidate.h",
+    "crypto_params.h",
     "data_channel_interface.cc",
     "data_channel_interface.h",
     "dtls_transport_interface.cc",