Add support for "Lethal Dose" support (for real this time)

[majochem]

Description of the problem being solved:

Mod parsing for "additional_poisons_+_to_apply_vs_non_poisoned_enemies" on Lethal Dose support was still missing and is now added

Steps taken to verify a working solution:

• Works with standard Viper Strike
• Only applies if NonPoisonedOnly is true (e.g. via config)
• Does not work with/benefit Viper Strike of the Mamba (because it can't apply multiple poisons)
• Also works with spells

Link to a build that showcases this PR:

Lethal Dose Test

After screenshot:

Mod parsing

Working with standard Viper Strike

"Not working" with Mamba