Also optimize strcture LootStoreItem that let use 4 byte for loot template element in memory instead 5 bytes.
But limit group id to 127 max value. Check this at loading.
* Replace reqClass by reqSkillVlaue field in `skill_discovery_template`
and check expected skill points amount for specific reipe discovery.
* Add new `spell_loot_template` loot table for store item selection data for spells.
At this moment for expclicit recipes discovery spells.
* Code cleanups.
Including fix _SCallback for 3 params, triggred mode correct call for .cast back and .cast target.
Remove outdated code for support old 19421 (and ranks) implementation in client data.
