Kernel: Implement hacky non-block read for ps2 keyboard

kernel/include/kernel/Input/PS2Keyboard.h

@@ -64,6 +64,7 @@ namespace Kernel::Input
 
 	protected:
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
+		virtual bool has_data_impl() const override;
 
 	private:
 		const dev_t m_rdev;

kernel/kernel/Input/PS2Keyboard.cpp

@@ -234,4 +234,10 @@ namespace Kernel::Input
 		}
 	}
 
+	bool PS2Keyboard::has_data_impl() const
+	{
+		CriticalScope _;
+		return !m_event_queue.empty();
+	}
+
 }