Add toggle of whether shield use ArmorMultiplier or not

[NetsuNegi]

In rulesmd.ini:

[CombatDamage]
ShieldApplyArmorMult=false            ; boolean

[SOMESHIELDTYPE]                      ; ShieldType name
ApplyArmorMult=                       ; boolean, default to [CombatDamage] -> ShieldApplyArmorMult

[github-actions]

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[phoboscn-bot]

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This pull request has been mentioned on Phobos CN. There might be relevant details there:

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此拉取请求已在 Phobos CN 上被提及。那里可能有相关详细信息：

https://www.phoboscn.top/t/topic/206/1

[Coronia]

tag names should be ApplyArmorMult for consistency

[TaranDahl]

Thought of a new issue. If the shield doesn't fully absorb the damage, does the armor modifier take effect twice?