Rename TapPacketReader to PollPacketReader for broader applicability * Renamed TapPacketReader to PollPacketReader to better reflect its functionality beyond TAP interface interaction. * The class includes general logic for polling and sending packets to file descriptors, making it suitable for wider use cases. Test: TH Change-Id: I5ed7d8ef62fc46c897fdefd85da7e925dee6af2c