Reland "p2p: add getters for local and remote ice parameters"

This is a reland of commit cff7428afb1c3ba12b679d9f7794108cdb18279c
providing a default implementation.

Original change's description:
> p2p: add getters for local and remote ice parameters
>
> Also makes the tests use those rather than individual accessors.
>
> BUG=webrtc:367395350
>
> Change-Id: I2cfef501957eed73cbb2e87c5c7306dc58247b41
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/383963
> Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
> Commit-Queue: Philipp Hancke <phancke@meta.com>
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#44368}

Bug: webrtc:367395350
Change-Id: Iaf98448ea854d03103609d0beea84b57455a9ecf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/386441
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@meta.com>
Cr-Commit-Position: refs/heads/main@{#44438}