Rework ipfw rules parsing and printing code.

Introduce show_state structure to keep information about printed opcodes.
Split show_static_rule() function into several smaller functions. Make
parsing and printing opcodes into several passes. Each printed opcode
is marked in show_state structure and will be skipped in next passes.
Now show_static_rule() function is simple, it just prints each part
of rule separately: action, modifiers, proto, src and dst addresses,
options. The main goal of this change is avoiding occurrence of wrong
result of `ifpw show` command, that can not be parsed by ipfw(8).
Also now it is possible to make some simple static optimizations
by reordering of opcodes in the rule.

PR:		[[ https://bugs.freebsd.org/222705 | 222705 ]]