feat(balance): large/huge mutants can attempt to wield ALWAYS_TWOHAND items one-handed

[chaosvolt]

Purpose of change (The Why)

Lil idea that came up in the BN server, letting larger mutants wield two-handed weapons they otherwise couldn't.

Describe the solution (The How)

In item.cpp, item::is_two_handed now lets Large and Huge mutants attempt to wield ALWAYS_TWOHAND items such as zweihanders in one hand. For Huge mutants they just outright get to wield them as easily as Medium characters try to wield normal items, but Large characters specifically need twice as much strength as normal to one-hand an item that has the ALWAYS_TWOHAND flag.

Describe alternatives you've considered

1. Simplifying it so that Large characters can one-hand two-handed weapons just as easily as Huge characters.
2. Making it so only Huge characters can try to do this.

Testing

Spawned a zweihander after equipping a shield. I can wield it if I'm Huge and my strength is 7, as expected. If I set myself to Large I need 14 strength to wield it with one hand, also as expected. When I'm back to Medium I go back to being unable to wield it one-handed at all.

Additional context

FIRE_TWOHAND was left unchanged in effect, since that's about actually having hands free to draw a bow or otherwise operate a complex ranged weapon, whereas ALWAYS_TWOHAND is solely about being able to wield weapons too large for normal humans.

Checklist

Mandatory

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