Junk pool rework

[fenhl]

Summarizing ideas discussed today for ways to make the way the junk pools are generated less arbitrary and more accurate to vanilla:

• The Deku stick refill is currently always in the junk pool even though it does not appear in chests in vanilla. It should only appear if locations that have stick refills (e.g. pots or MQ Jabu chests) are shuffled. I think we should refactor how junk items are generated to:
  1. Start with all shuffled junk items in the pool (depends on settings)
     • Some locations (e.g. cows, enemy drops) don't have vanilla items; these should be skipped
  2. Remove or duplicate until there are exactly enough items to fill all shuffled locations* There are some locations that can drop magic refills (e.g. some wonderitems, and the “Fix Broken Drops” setting could probably apply to the chests in Shadow temple), but the item pool doesn't reflect that. This is waiting for the release after 8.3 to reduce confusion from the magic meter model change.
• We currently don't handle the vanilla behavior of some recovery hearts upgrading to green rupees on full health.
• There are some locations that drop randomized items (e.g. grass shuffle which @rrealmuto is working on). We should simulate these drop tables at seed generation time to avoid a situation where a freestanding item changes between scene reloads. Flex drops would have to be runtime upgrades though.