Consolidate sequence analysis code.

Move scattered code for seq_analysis_info_t creation and destruction to
tap-sequence-analysis.[ch].

Change-Id: I87c14b1c83105a48d0ab149a3abba71e2a2fe21f
Reviewed-on: https://code.wireshark.org/review/5479
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Gerald Combs <gerald@wireshark.org>