Don't assume string_view::iterator is const char* #4849

Job	Run time
KytheVerification	0s
ClangTidy	5m 17s
CheckFormatAndBuildClean	1m 53s
x86_64 test	3m 37s
arm64 test	4m 22s
KytheXrefs	0s
x86_64 test-clang	4m 14s
MacOsBuild	3m 50s
arm64 test-clang	4m 16s
PrepareVSPlugin	2m 7s
x86_64 test-nortti	3m 49s
WindowsBuild	10m 40s
x86_64 test-c++20	3m 48s
x86_64 test-c++23	3m 47s
x86_64 smoke-test	11m 46s
arm64 smoke-test	12m 41s
x86_64 asan	5m 18s
x86_64 asan-clang	4m 48s
x86_64 compile	4m 29s
arm64 compile	3m 55s
x86_64 compile-clang	3m 17s
arm64 compile-clang	3m 48s
x86_64 compile-static	3m 14s
arm64 compile-static	4m 2s
x86_64 compile-static-clang	3m 17s
arm64 compile-static-clang	3m 42s
x86_64 clean	7m 12s
arm64 clean	6m 52s
Build and deploy GitHub pages	7s
📦 Release	0s
	2h 10m 8s

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