[Enchantment] - Use selector (from 0 to 16) for GroupID for *_loot_template and increase the colour pallete up to 16

We currently (keira) supports 1 to 9 to get colours, it's suggested that this shouldn't go above 16.

> Note: The client can only display 16 items in the loot windows, this includes gold. Therefore it is not recomended to use more than 16 groups.

Selector makes sure the user doesn't use non intended values.

Start in the GroupID controls and colour-palette implementation for *_loot_template entries. Check how values from 1 to 9 are currently selected and displayed, then verify the selector permits 0 through 16 and the palette supports 16 groups while respecting the client’s 16-item loot-window limit.

Written by the indexing model from the issue text.