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: Icdf9a9d7ef6f49b589ed9cdbd05159ab95e7e5d9
20 files changed