L2SS-867: Move statistics_writer into statistics module

tangostationcontrol/setup.cfg

...oncontrol/integration_test/default/statistics/__init__.py

...ol/integration_test/default/statistics/test_writer_sst.py

...ol/integration_test/default/statistics_writer/__init__.py

tangostationcontrol/tangostationcontrol/statistics/writer.py

...ngostationcontrol/statistics_writer/udp_dev/udp_client.py

...ationcontrol/tangostationcontrol/test/beam/test_delays.py

...ioncontrol/test/statistics/SDP_BST_statistics_packets.bin

...tioncontrol/test/statistics/SDP_SST_statistics_packet.bin

...ioncontrol/test/statistics/SDP_SST_statistics_packets.bin

...ioncontrol/test/statistics/SDP_XST_statistics_packets.bin

...atistics/SDP_XST_statistics_packets_multiple_subbands.bin

...ontrol/tangostationcontrol/test/statistics/test_writer.py