GH-88418
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Validate extension JSON: API was removed: classes/GDExtension/methods/close_library
Validate extension JSON: API was removed: classes/GDExtension/methods/initialize_library
Validate extension JSON: API was removed: classes/GDExtension/methods/open_library

Since it was basically impossible to use these methods in any useful way, the GDExtension team agreed that breaking compatibility by removing them was OK.
