Add static method for HTTPClient's `query_string_from_dict` #540

Job	Run time
📊 Static checks / Code style, file formatting, and docs	3m 11s
🍏 iOS / Template (target=template_release)	34m 8s
🐧 Linux / Editor w/ Mono (target=editor)	38m 22s
🤖 Android / Template (target=template_release)	29m 46s
🐧 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)	39m 58s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	33m 2s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	29m 55s
🍎 macOS / Editor (target=editor, tests=yes)	48m 46s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	21m 24s
🐧 Linux / Template w/ Mono (target=template_release)	24m 19s
🍎 macOS / Template (target=template_release)	16m 29s
🌐 Web / Template w/o threads (target=template_release, threads=no)	21m 47s
🐧 Linux / Minimal template (target=template_release, everything disabled)	14m 32s
🏁 Windows / Editor (target=editor, tests=yes)	43m 43s
🏁 Windows / Template (target=template_release)	33m 28s
🪲 Godot CPP / Build and test Godot CPP	7m 4s
	7h 19m 54s

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