add emerald key node information to map state screen

[OutOfBrain]

This way we can react on the flame-elite to chase the emerald key.

This helps the guys over at https://github.com/xaved88/bottled_ai/ with their bot and beating the final boss.

[Typhi]

looks good from my testing:

• doesn't show on not map screen ✅
• shows on map screen before picking it up ✅
• shows on map screen after picking it up ✅yeah fine whatever
• doesn't show on the next act map when it has already been acquired in previous act ✅
• doesn't show on a game file that hasn't unlocked it yet ✅

combos nicely with the act 4 keys object that was added already here: #15

[JonJac]

I would love if this was merged