Applying CA1834 - Use StringBuilder.Append(char) for single character strings #1203

Job	Run time
cpp-lib-build (macos-15, clang, ON)	43s
cpp-lib-build (macos-15, clang, OFF)	48s
build (macos-15, tool)	1m 11s
cpp-lib-build (macos-15, gcc, ON)	51s
build (macos-15, cpp)	9m 42s
cpp-lib-build (macos-15, gcc, OFF)	46s
build (macos-15, csharp)	5m 46s
cpp-lib-build (ubuntu-20.04, clang, ON)	58s
build (macos-15, dart)	8m 38s
cpp-lib-build (ubuntu-20.04, clang, OFF)	59s
cpp-lib-build (ubuntu-20.04, gcc, ON)	46s
build (macos-15, go)	1m 53s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	48s
build (macos-15, java)	1m 9s
build (macos-15, javascript)	1m 40s
cpp-lib-build (windows-2022, clang, ON)	4m 12s
build (macos-15, typescript)	8m 15s
cpp-lib-build (windows-2022, clang, OFF)	5m 27s
build (macos-15, php)	1m 48s
cpp-lib-build (windows-2022, cl)	4m 19s
build (macos-15, python3)	1m 16s
build (ubuntu-20.04, tool)	1m 2s
build (ubuntu-20.04, cpp)	16m 5s
build (ubuntu-20.04, csharp)	5m 25s
build (ubuntu-20.04, dart)	3m 42s
build (ubuntu-20.04, go)	2m 39s
build (ubuntu-20.04, java)	1m 6s
build (ubuntu-20.04, javascript)	1m 25s
build (ubuntu-20.04, typescript)	10m 25s
build (ubuntu-20.04, php)	1m 14s
build (ubuntu-20.04, python3)	1m 13s
build (windows-2022, tool)	1m 58s
build (windows-2022, cpp)	24m 5s
build (windows-2022, csharp)	9m 1s
build (windows-2022, dart)	4m 34s
build (windows-2022, go)	6m 43s
build (windows-2022, java)	2m 18s
build (windows-2022, javascript)	2m 33s
build (windows-2022, typescript)	20m 31s
build (windows-2022, php)	2m 40s
build (windows-2022, python3)	1m 54s
	3h 2m 28s

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