MINOR: tcp-rules: Make tcp-request capture a custom action

MINOR: tcp-rules: Make tcp-request capture a custom action

Now, this action is use its own dedicated function and is no longer handled "in
place" during the TCP rules evaluation. Thus the action name ACT_TCP_CAPTURE is
removed. The action type is set to ACT_CUSTOM and a check function is used to
know if the rule depends on request contents while there is no inspect-delay.