Add mark_scene_as_saved method #268

Job	Run time
📊 Static checks / Code style, file formatting, and docs	1m 10s
🍏 iOS / Template (target=template_release)	9m 15s
🍎 macOS / Editor (target=editor, tests=yes)	44s
🐧 Linux / Editor w/ Mono (target=editor)	21m 4s
🤖 Android / Editor (target=editor)	26m 29s
🍎 macOS / Template (target=template_release, tests=yes)	38s
🐧 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)	34m 41s
🤖 Android / Template arm32 (target=template_release, arch=arm32)	16m 58s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	35m 44s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	25m 3s
🤖 Android / Template arm64 (target=template_release, arch=arm64)	17m 26s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	31m 16s
🌐 Web / Template w/o threads (target=template_release, threads=no)	26m 34s
🏁 Windows / Editor (target=editor, tests=yes)	29m 41s
🐧 Linux / Template w/ Mono (target=template_release, tests=yes)	27m 35s
🏁 Windows / Editor w/ clang-cl (target=editor, tests=yes, use_llvm=yes)	46m 9s
🐧 Linux / Minimal template (target=template_release, tests=yes, everything disabled)	14m 10s
🏁 Windows / Template (target=template_release, tests=yes)	36m 5s
🪲 Godot CPP	0s
	6h 40m 42s

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