Basic unitsorts for hjson (#6280)

* Create some basic unitSorts

* Set as defaults

* add to ContentParser

core/src/mindustry/entities/UnitSorts.java

@@ -0,0 +1,14 @@
+package mindustry.entities;
+
+import arc.math.*;
+import mindustry.entities.Units.*;
+import mindustry.gen.*;
+
+public class UnitSorts{
+    public static Sortf
+
+    closest = Unit::dst2,
+    farthest = (u, x, y) -> -u.dst2(x, y),
+    strongest = (u, x, y) -> -u.maxHealth + Mathf.dst2(u.x, u.y, x, y) / 6400f,
+    weakest = (u, x, y) -> u.maxHealth + Mathf.dst2(u.x, u.y, x, y) / 6400f;
+}