Fix combat skill item requirements

[themrrobert]

Description:

Fixes issue where black mask, and other items with combat skill requirements are broken / unequippable.

Changes:

• Creates new type, SkillRequirements, that does contain combat. There is already a similar type, ItemRequirements (in OSJS), but the new SkillRequirements type exists with all of the other skill requirement code in the bot (not in OSJS), so I think this makes the most sense.

Other checks:

• [ ] I have tested all my changes thoroughly.