Reland "sdk: add RTC_OBJC_TYPE to ios Metal renderer classes"

This is a reland of commit 89e8619bfdacfd1364bf3fc6bc5388c92629ab71

Original change's description:
> sdk: add RTC_OBJC_TYPE to ios Metal renderer classes
>
> Bug: webrtc:460166677
> Change-Id: Id8883d40957e26046897632c4f6ed2d9c36bcf4e
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/427320
> Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
> Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#46309}

Bug: webrtc:460166677
Change-Id: Ia31eec951ca8c3dbe2389b8b0244ce0d540bfcc1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/430900
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#46595}