Damage should use a struct object, rather than passing around raw values

[LeagueSandboxBot]

See Title. Currently, TakeDamage takes four arguments (a float, a DamageType enum, a DamageSource enum, and a bool that determines if the damage is a critical hit) that could easily be put into a struct.

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Beep, boop, I'm a bot! This issue was created by @Pokémonred200 in #development.