Add support for Runeforged/mastered unique variants

[vaisest]

Description of the problem being solved:

This adds support for runeforged/mastered base variants in the unique DB. This does not change the default behaviour as an item due to e.g. the level requirements using the unique DB. I'm also not really sure defaulting to the best variant is desired since I'm not sure how exactly people use the item DB.

This is done by adding a new tag which works similarly to variants, but is treated as its own group, similar to what has been done with unique versions:

Rarity: UNIQUE
Atziri's Step
Cinched Boots
Evasion: 533
League: Fate of the Vaal
Base Variant: Regular Base
Base Variant: Runeforged
Base Variant: Runemastered
Selected Base Variant: 3
{base:1}Cinched Boots
{base:2}Runeforged Cinched Boots
{base:3}Runemastered Cinched Boots
Quality: 20
LevelReq: 65
Implicits: 0
30% increased Movement Speed
{range:0.5}(80-120)% increased Evasion Rating
{range:0.5}+(70-100) to maximum Life
{range:0.5}Gain Deflection Rating equal to (40-60)% of Evasion Rating
{range:0.5}-(12-6)% to amount of Damage Prevented by Deflection
Cannot be Light Stunned by Deflected Hits

This should also work with versioning, if that is even necessary:

Rarity: Unique
Versioned Base Variant Test
{version:1}{base:1}Gold Ring
{version:1}{base:2}Iron Ring
{version:2}{base:1}Ruby Ring
{version:2}{base:2}Amethyst Ring
Version: Legacy
Version: Current
Selected Version: 1
Base Variant: Gold/Ruby
Base Variant: Iron/Amethyst
Selected Base Variant: 2
Implicits: 0
{version:1}+10 to maximum Life
{version:2}+20 to maximum Life

Steps taken to verify a working solution:

• Automated tests added

Link to a build that showcases this PR:

Before screenshot:

After screenshot: