Refactor source layout

Introduce compat source sets and move all kotlin sources to the main directory

[no changelog]

src/main/kotlin/features/world/NavigableWaypoint.kt

@@ -0,0 +1,22 @@
+package moe.nea.firmament.features.world
+
+import io.github.moulberry.repo.data.NEUItem
+import net.minecraft.util.math.BlockPos
+import moe.nea.firmament.util.SkyBlockIsland
+
+abstract class NavigableWaypoint {
+    abstract val name: String
+    abstract val position: BlockPos
+    abstract val island: SkyBlockIsland
+
+    data class NPCWaypoint(
+        val item: NEUItem,
+    ) : NavigableWaypoint() {
+        override val name: String
+            get() = item.displayName
+        override val position: BlockPos
+            get() = BlockPos(item.x, item.y, item.z)
+        override val island: SkyBlockIsland
+            get() = SkyBlockIsland.forMode(item.island)
+    }
+}