Fix Mob#isInDaylight not being accurate

[Warriorrrr]

isSunBurnTick includes a call to random, which makes this method return false for most of the time all the while the enitty is in full daylight. This new implementation partly copies that method, minus the monsters burn environment attribute check and the random call, to be more accurate and useful.

[lynxplay]

Soooo, while removing the random here is fine, the method definitely wasn't just a "is somehow under daylight".
The in water check was there since its addition in 1.13.1 and poweder snow etc is carried over.
That means that really we are more checking if in sun and possibly about to burn, which also means we should be respecting bools controlled by org.bukkit.entity.AbstractSkeleton#setShouldBurnInDay, which override the method internally.

Probably best solved via bool params on the sunburn tick method?

[Warriorrrr]

#13491 removes the overrides the existing shouldBurnInDay api has, it would seem pretty counterintuitive to me that an entity not burning in daylight would mean that they are not considered to be in daylight by this method, that same PR adds a new method that answers the question of whether this mob would burn if it were to be exposed to daylight.

Not sure what would be best for this method, the changes I've pushed now just pass a bool to the method to skip the random, which should hopefully make this PR fine regardless of what happens to the other one.