REGTESTS: tcp-rules: test the set-src, set-dst and port rewriting actions

REGTESTS: tcp-rules: test the set-src, set-dst and port rewriting actions

set-src-port and set-dst-port had no coverage at all, and set-src and
set-dst were only used incidentally by other tests.

The test applies them from the "tcp-request connection", "tcp-request
session", "tcp-request content" and "http-request" rule sets and checks
the documented behaviors: set-src and set-dst preserve the port while
set-src-port and set-dst-port preserve the address, and a later rule set
overrides what an earlier one did.

It also shows that a rewrite performed from a "tcp-request connection"
rule alters the connection itself, so that fc_src and fc_dst report the
new values, while a rewrite performed at the session level leaves them
untouched.