Add RSE Trades, remove non-zubat encounters from altering cave in Emerald

[notblisy]

This commit seeks to do two things:

1. Add all the trade encounters from this article: https://bulbapedia.bulbagarden.net/wiki/In-game_trade#Generation_III into Ruby, Sapphire, and Emerald

2. Remove the non zubat altering cave encounters as described in this issue: Question: Should altering cave encounters be removed from FRLG/Emerald #1457

To add the trades, I added a few things:

• New location area for foretree city

• relevant encounters and encounter slots

• encounter conditions for which pokemon to trade

• relevant prose

To remove altering cave I:

• Removed all non-zubat encounters from encounters.csv

• Removed all hoenn altering cave location areas except 441, and removed its name "a".

• removed relevant prose.

Contributor check list

• I have written a description of the contribution and explained its motivation.
• I have written tests for my code changes (if applicable).
• I have read and understood the AI Assisted Contribution guidelines.
• I will own this change in production, and I am prepared to fix any bugs caused by my code change.

[jemarq04]

Looks great, thanks!

[jemarq04]

Maybe we can wait before merging this one to give @ItsMeJoji some time to update their branch so it can be merged first to avoid #1476 from going stale again.