DIM export: Automatically add a class item that fits the selection

[Mijago]

This goes hand-in-hand with https://github.com/Mijago/D2ArmorPicker/issues/114.

• Make sure the class item fits the requirements
• Be smart in selecting it: masterworked, maybe use one in the inventory, etc, etc.

[TheMojoDojo]

Considering tackling #99 along this

filtering artifice with modslot:artifice may be an applicable alternative to the current perkname:"artifice armor"

[TheYeshir13]

maybe add a toggle to disable class-item selection at all (as a first easy fix)