Refactor source layout

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

[no changelog]

src/main/kotlin/events/HandledScreenPushREIEvent.kt

@@ -0,0 +1,18 @@
+
+
+package moe.nea.firmament.events
+
+import me.shedaniel.math.Rectangle
+import net.minecraft.client.gui.screen.ingame.HandledScreen
+
+data class HandledScreenPushREIEvent(
+    val screen: HandledScreen<*>,
+    val rectangles: MutableList<Rectangle> = mutableListOf()
+) : FirmamentEvent() {
+
+    fun block(rectangle: Rectangle) {
+        rectangles.add(rectangle)
+    }
+
+    companion object : FirmamentEventBus<HandledScreenPushREIEvent>()
+}