Added Scale Feature for Mobs with Levels

[Fly1337]

In this PR, I added the requested feature in #9 . Mobs can now have different sizes based on two valid entries:

50-100: chance: 0.5 scale: 1-2
This allows mobs between the levels 50-100 to have a 50% of being between the sizes 1 and 2. The other option is:

10-100: chance: 1.0 scale: 1, 2, 3
This allows mobs between the levels 1-100 to have the sizes 1, 2 or 3.

For the code, the functionality is handled over a new class called ScaleUtil that has a method to load the config and also apply the scale. With this, the config can easily be reloaded by the reload command and API-Access for applying the scale is also given. The class also holds a private inner class called ScaleEntry that holds all values.

Further, all entries are stored in a LinkedList, so they are stored on a linear basis which allows later entries to perhaps override entities with a smaller chance to a different size.

As discussed on Discord, the PR also contains the change for the PlaceholderAPI repo.

Lmk if there is something change

I also append screenshots of blazes using the feature as well as a spider once which naturally spawned

PS: Yes, I've messed up a commit due to debug outputs

[Archy-X]

For consistency in code style and to follow best practice, I've made comments mostly about removing static fields and methods.