loot: enforce minCount == maxCount for reference loot entries

[sudlud]

Right now when editing loot, the minCount field is not beeing shown for reference loot entries because it is not supported by the core.
Keira will set it to default = 1 if I've seen it correctly. this leads to entries beeing added with minCount < maxCount.

I'd like to have Keira "enforce" that it's beeing set to the same value as maxCount because then it's clear to anyone looking at the loot templates that there's no variation for reference loot entries.

I'm also introducing a core side startup check for this right now so it would be nice to have Keira support anyone editing these :)

azerothcore/azerothcore-wotlk#20725

The goal is to avoid misconfiguring loot templates.