Reland "Remove stringstream fallback from MakeVal in logging.h"

This is a reland of commit 4ccdad97fcb69489aa4c77593dbc382bbd532997

Before relanding, the RTC_LOG macro will be updated to support
std::string_view explicitly to avoid previous implicit conversion
problems between absl::string_view, std::string and std::string_view.

Original change's description:
> Remove stringstream fallback from MakeVal in logging.h
>
> This change removes the generic MakeVal fallback in logging.h that
> relied on std::ostringstream. This hasn't been used in webrtc for years
> but now known downstream dependencies have been removed in favor of more
> efficient alternatives like StringBuilder and Abseil's string utilities.
>
> Existing call sites and related code in tests and tools have similarly
> been migrated:
>
> * Replaced std::ostringstream and std::stringstream with StringBuilder
>   in SDP, Opus, and OpenSSL unit tests.
> * Refactored string parsing in neteq_quality_test and bwe_rtp to use
>   absl::StrSplit and Abseil's numeric conversion functions.
> * Updated RTC_LOG calls in cross_traffic_unittest to explicitly load
>   atomic counters (and not rely on stringstream to do it).
> * Updated BUILD.gn and DEPS to include required Abseil and string
>   utility dependencies.
>
> Bug: webrtc:42234461
> Change-Id: I7fbe4b68478fb1aca08c6126979ae577ef5418da
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/466441
> Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
> Reviewed-by: Jakob Ivarsson‎ <jakobi@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#47577}

Bug: webrtc:42234461
Change-Id: I2ff763f1ae1c08499396ad97767375392af6c7c3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/469260
Reviewed-by: Jakob Ivarsson‎ <jakobi@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47616}