Common base class

Currently both DynamicCore and StaticCore extend HybridCore. This is a bit strange inheritance hierarchy in general, but it's especially stupid to check does a library extend any of these by using isinstance(library, HybridCore). It would be better to have a common base class named LibraryCore or RobotLibraryCore that all concrete lib cores extend. It would allow using isinstance(library, RobotLibraryCore).

Until this common base class is implemented, it's probably best to use isinstance(library, (HybridCore, DynamicCore, StaticCore)) with any generic code. That's both more explicit than just using isinstance(library, HybridCore) and also works if and when other cores don't anymore extend HybridCore.

先找出 HybridCore、DynamicCore 和 StaticCore 的定義與使用位置。檢視共用的 LibraryCore 或 RobotLibraryCore 會如何影響繼承與通用的 isinstance 檢查；完成的標準是具體的 core 共用新的基底類別，而不依賴 HybridCore 作為共用型別。