[lua] xi.itemUtils.pickItemRandom tidy

[MowFord]

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• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
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• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Continues the work from here. Updates another itemUtil to create a lootTable of a single lootGroup and use the util from the previous PR

I would also like to move the lootTable util utils.selectFromLootGroups over to itemUtils, but didn't want to do that unless i got confirmation that is wanted (it would make more sense to rename it xi.itemUtils.selectFromLootGroups, I would think?)

I also was going to update nyzul item appraisals, but i'll leave that for another PR as it's also a ton of find/replace to add itemId/weight keys

For now, this PR

• updates the itemUtil helper and squashes a few more bespoke "sum weights and loop over the table of items" functions
  • casket_loot.lua was updated with the following sed, then used the new LLS editorconfig to autoformat
  • sed -E 's/\{\s*(xi\.item\.[^,]+)(,\s*)([0-9]+)/{ itemId = \1\2weight = \3/' casket_loot.lua -i
• removes the splitZones set as the casket_loot having a Hi/Low table indicates if it's a split zone already
• streamlines some table[math.random(#table)] calls to use utils.randomEntry

Steps to test these changes

• !additem 26955
  • equip and use it to get meat
  • 
• caskets
  • change settings CASKET_DROP_RATE = 1
  • go killin mobs, spawn chests, see they drop items all the same
  • 
  • 

[Xaver-DaRed]

Rebase please