Don't assume string_view::iterator is const char* #4841

Job	Run time
ClangTidy	2m 35s
x86_64 test	2m 48s
KytheVerification	0s
CheckFormatAndBuildClean	29s
arm64 test	3m 27s
MacOsBuild	7m 44s
x86_64 test-clang	2m 50s
arm64 test-clang	3m 25s
PrepareVSPlugin	2m 14s
WindowsBuild	8m 36s
x86_64 test-nortti	2m 52s
x86_64 test-c++20	2m 52s
KytheXrefs	0s
x86_64 test-c++23	2m 46s
x86_64 smoke-test	10m 36s
arm64 smoke-test	11m 32s
x86_64 asan	3m 33s
x86_64 asan-clang	3m 5s
x86_64 compile	2m 59s
arm64 compile	3m 30s
x86_64 compile-clang	2m 48s
arm64 compile-clang	3m 30s
x86_64 compile-static	2m 47s
arm64 compile-static	3m 19s
x86_64 compile-static-clang	2m 46s
arm64 compile-static-clang	3m 23s
x86_64 clean	2m 31s
arm64 clean	3m 24s
Build and deploy GitHub pages	1s
📦 Release	1s
	1h 42m 23s

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