Add tests for `replace_chars` #3214

Job	Run time
📊 Static checks / Code style, file formatting, and docs	27s
🍎 macOS / Editor (target=editor, tests=yes)	24m 26s
🤖 Android / Editor (target=editor)	22m 16s
🍎 macOS / Template (target=template_release)	17m 7s
🐧 Linux / Editor w/ Mono (target=editor)	34m 38s
🤖 Android / Template arm32 (target=template_release, arch=arm32)	13m 50s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	40m 39s
🍏 iOS / Template (target=template_release)	7m 43s
🤖 Android / Template arm64 (target=template_release, arch=arm64)	13m 38s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	32m 4s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	28m 29s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	21m 43s
🐧 Linux / Template w/ Mono (target=template_release)	22m 39s
🌐 Web / Template w/o threads (target=template_release, threads=no)	23m 7s
🏁 Windows / Editor (target=editor, tests=yes)	44m 59s
🐧 Linux / Minimal template (target=template_release, everything disabled)	14m 0s
🏁 Windows / Editor w/ clang-cl (target=editor, tests=yes, use_llvm=yes)	39m 24s
🏁 Windows / Template (target=template_release)	31m 44s
🪲 Godot CPP / Build and test Godot CPP	8m 15s
	7h 21m 8s

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