rewrite ShieldBonusMod into ShieldStrengthMod

[k0l11]

There needs to be a way to add a shield strength mod to a character (shield strength is a hidden character stat), because as it is the implementation of the following things is incorrect: resonance:

• [ ] geo resonance

character abilities:

• [ ] thoma a1
• [ ] zhongli a1

artifact sets:

• [ ] retracing bolide
• [ ] tenacity of the millelith

weapons:

• [ ] Memory of Dust
• [ ] Summit Shaper
• [ ] The Unforged
• [ ] Vortex Vanquisher

Don't forget that the rewritten mods should also be hitlag extendable.