Revert "Remove the deprecated libjingle_peerconnection target"

This reverts commit 77889f4867c822547908093eaa240b34eb086303.

Reason for revert: Downstream projects need to be updated first.

Original change's description:
> Remove the deprecated libjingle_peerconnection target
>
> Change-Id: I0dc50fb3aa239b3f4c509e86e25a55bf6b595a8d
> Bug: webrtc:463418937
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/479160
> Commit-Queue: Jeremy Leconte <jleconte@google.com>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#47928}

Bug: webrtc:463418937
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I5b6cf3907432ad69d6c4fca5de2b7d762954f4e5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/479940
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47936}