Refactor source layout

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

[no changelog]

src/main/kotlin/features/debug/DebugLogger.kt

@@ -0,0 +1,13 @@
+
+package moe.nea.firmament.features.debug
+
+import net.minecraft.text.Text
+import moe.nea.firmament.util.MC
+
+class DebugLogger(val tag: String) {
+    fun isEnabled() = DeveloperFeatures.isEnabled // TODO: allow filtering by tag
+    fun log(text: () -> String) {
+        if (!isEnabled()) return
+        MC.sendChat(Text.literal(text()))
+    }
+}