Adopt absl::string_view in function parameters under rtc_base/

This is part of a large-scale effort to increase adoption of
absl::string_view across the WebRTC code base.

This CL converts the majority of "const std::string&"s in function
parameters under rtc_base/ to absl::string_view.

Bug: webrtc:13579
Change-Id: I2b1e3776aa42326aa405f76bb324a2d233b21dca
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/254081
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Xavier Lepaul‎ <xalep@webrtc.org>
Reviewed-by: Anders Lilienthal <andersc@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Ali Tofigh <alito@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36239}
diff --git a/rtc_base/string_utils.cc b/rtc_base/string_utils.cc
index c034335..e8c1346 100644
--- a/rtc_base/string_utils.cc
+++ b/rtc_base/string_utils.cc
@@ -10,6 +10,8 @@
 
 #include "rtc_base/string_utils.h"
 
+#include "absl/strings/string_view.h"
+
 namespace rtc {
 
 size_t strcpyn(char* buffer,