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
2 files changed