Add autocompletion for RenderingServer's global shader & has_os_feature #288

Job	Run time
📊 Static checks / Code style, file formatting, and docs	2m 44s
🐧 Linux / Editor w/ Mono (target=editor)	34m 23s
🤖 Android / Template (target=template_release)	27m 48s
🐧 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)	35m 39s
🌐 Web / Template (target=template_release)	20m 36s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	32m 8s
🍏 iOS / Template (target=template_release)	19m 36s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	28m 18s
🐧 Linux / Template w/ Mono (target=template_release)	22m 53s
🐧 Linux / Minimal template (target=template_release, everything disabled)	14m 37s
🏁 Windows / Editor (target=editor, tests=yes)	40m 58s
🍎 macOS / Editor (target=editor, tests=yes)	24m 43s
🏁 Windows / Template (target=template_release)	29m 28s
🍎 macOS / Template (target=template_release)	29m 42s
🪲 Godot CPP / Build and test Godot CPP	6m 41s
	6h 10m 14s

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