Implement GDExtension support #131

Job	Run time
🧪 Unit tests	4m 22s
🐧 Linux / Editor (x86_64, release)	15m 23s
🐧 Linux / Template (x86_64, release)	10m 46s
🔌 GDExtension / 🐧 Linux (x86_64, release)	1m 25s
🔌 GDExtension / 🐧 Linux (x86_64, debug)	1m 20s
🔌 GDExtension / 🪟 Windows (x86_64, release)	2m 57s
🍎 macOS / Editor (x86_64, release)	10m 39s
🪟 Windows / Editor (x86_64, release)	10m 23s
🍎 macOS / Editor (arm64, release)	6m 31s
🪟 Windows / Editor .NET (x86_64, release)	12m 47s
🔌 GDExtension / 🪟 Windows (x86_64, debug)	2m 42s
🔌 GDExtension / 🍎 macOS (universal, release)	1m 36s
🔌 GDExtension / 🍎 macOS (universal, debug)	1m 43s
🍎 macOS / Make macOS Bundles	1m 30s
	1h 24m 4s

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