Determine number of encounters per area

[MrTyton]

Determine the number of encounters that we will get in an area through RNG lookahead.

https://grayfox96.github.io/FFX-Info/rng/encounters#encounter-checks for reference

This will require a few things:

1. Determining how many units of movement the TAS does in each area
2. Map these relative to the grace periods
3. Use RNG0 to determine how many encounters we will get
4. Use RNG1 to determine what the encounters are

Once we have that framework, we can work into much longer manips using that information.