Assistant: Add missing bitmap accessor for terminal actions

Author: https://github.com/gunnarbeutner
Commit: 6af08f950a
Pull-request: https://github.com/SerenityOS/serenity/pull/8410

Userland/Applications/Assistant/Providers.h

@@ -106,6 +106,8 @@ public:
     ~TerminalResult() override = default;
     void activate() const override;
 
+    virtual Gfx::Bitmap const* bitmap() const override { return m_bitmap; }
+
 private:
     RefPtr<Gfx::Bitmap> m_bitmap;
 };