Missile uclass flag to the ruleset
Split from Feature #783336
Move the Missile unit class flag to the ruleset and lift the restriction that a unit that can perform "Suicide Attack" can't perform regular attacks.
This makes units that can attack the normal way but also perform suicide attacks possible. Rules for what circumstances permits regular attack and what circumstances permits suicide attacks are action enabler controlled. Example rule: an air unit that has to perform a Kamikaze attack to fight sea units. It has combat bonuses against sea units to make the Kamikaze attack worth performing.