Add Bi-entity Condition and Action fields to `apoli:modify_damage_dealt` and `apoli:modify_damage_taken`

[MerchantPug]

Modify Damage Dealt.

modify_damage_dealt is fairly straightforward since a target always exists in this case.

Basically it handles the check as you'd expect it to. Being that if the bi-entity condition is null or the power holder and target fit the condition, it returns true.

Modify Damage Taken

We've discussed the issue with adding a bientity condition to modify_damage_taken before, however I've come up with a solution for this.

If you have a bientity_condition field specified, the damage source requires an attacker to actually work, with the non attacker damage condition only returning true if the bientity_condition is null.

If there is an attacker it'll check for if the bientity condition is null or if the attacker and power holder respectively the fits the bientity condition.

[MerchantPug]

I imagine there are some issues within this PR so please bring them up with me.