HashMap: Allow hashing of differently typed keys #304

Job	Run time
📊 Static checks / Code style, file formatting, and docs	29s
🍏 iOS / Template (target=template_release)	8m 31s
🍎 macOS / Editor (target=editor, tests=yes)	1m 57s
🤖 Android / Editor (target=editor)	21m 56s
🍎 macOS / Template (target=template_release)	1m 32s
🐧 Linux / Editor w/ Mono (target=editor)	36m 9s
🐧 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)	43m 28s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	33m 42s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	23m 33s
🏁 Windows / Editor (target=editor, tests=yes)	2m 50s
🤖 Android / Template arm32 (target=template_release, arch=arm32)	14m 18s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	29m 44s
🌐 Web / Template w/o threads (target=template_release, threads=no)	23m 17s
🏁 Windows / Template (target=template_release)	3m 20s
🐧 Linux / Template w/ Mono (target=template_release)	22m 29s
🐧 Linux / Minimal template (target=template_release, everything disabled)	14m 44s
🤖 Android / Template arm64 (target=template_release, arch=arm64)	14m 11s
🪲 Godot CPP / Build and test Godot CPP	8m 2s
	5h 4m 12s

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