Refactor source layout

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

[no changelog]

src/main/kotlin/util/MinecraftDispatcher.kt

@@ -0,0 +1,8 @@
+
+
+package moe.nea.firmament.util
+
+import kotlinx.coroutines.asCoroutineDispatcher
+import net.minecraft.client.MinecraftClient
+
+val MinecraftDispatcher by lazy { MinecraftClient.getInstance().asCoroutineDispatcher() }