Add Point Of Interest API

[Y2Kwastaken]

The goal of this Pull Request is to add a basic level of support for Point of Interest in the API. This more used within entity AI, however, there can be exposed a useful detect Point of interests in the world. I want to flesh this out if possible, however I also want testing to be done on the current API to make sure it works as intended.

I will work more on testing and seeing if this API can be fleshed out more in the coming days/weeks.

[Y2Kwastaken]

Is there any way in specific we should handle this case

Just tested this, and will I get the expected result for Villager workstation (specifically farmer).
I do not get the result for beehives.
For beehives it gets only found for occupancy ANY, and returns null for the other two ones. Regardless if it is empty, 1 / 2 Bees or full.

I got this comment on spigot a few months ago. Do we either

1. specify the discrepancy in the API documentation
2. each PoiType internal would run through something like CraftMenus but for PaperPoiTypes etc that will map to some Predicate that can make up for the non straightforward discrepancies. This isn't super straightforward and kind of annoying, but it does "fix" some things internals is a bit uneven about.

[Owen1212055]

I think that documenting the fact that some POITypes are used more as "markers" for the block rather than storing occupancy would be useful.

Could maybe even add a method onto the poi type class if it has 0 max tickets so people can check themselves.