Implement GDExtension support #132

Job	Run time
🧪 Unit tests	4m 21s
🐧 Linux / Editor (x86_64, release)	15m 24s
🔌 GDExtension / 🐧 Linux (x86_64, release)	1m 27s
🐧 Linux / Template (x86_64, release)	10m 41s
🔌 GDExtension / 🐧 Linux (x86_64, debug)	1m 16s
🍎 macOS / Editor (x86_64, release)	10m 0s
🔌 GDExtension / 🪟 Windows (x86_64, release)	2m 41s
🍎 macOS / Editor (arm64, release)	12m 29s
🔌 GDExtension / 🪟 Windows (x86_64, debug)	3m 53s
🪟 Windows / Editor (x86_64, release)	9m 37s
🔌 GDExtension / 🍎 macOS (universal, release)	1m 26s
🪟 Windows / Editor .NET (x86_64, release)	12m 50s
🔌 GDExtension / 🍎 macOS (universal, debug)	3m 13s
🍎 macOS / Make macOS Bundles	1m 35s
	1h 30m 53s

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