Add logging functionality and Maven publishing setup

Added Logger class with various log levels to `commonMain`. Integrated `maven-publish` and `signing` plugins in `build.gradle.kts` to facilitate publishing artifacts to the Maven repository with proper credentials and metadata. Removed `gradle.properties` and updated `.gitignore` accordingly.

src/commonMain/kotlin/nl/astraeus/logger/Logger.kt

@@ -0,0 +1,52 @@
+package nl.astraeus.logger
+
+enum class LogLevel {
+  TRACE,
+  DEBUG,
+  INFO,
+  WARN,
+  ERROR,
+  FATAL
+}
+
+class Logger(
+  var level: LogLevel = LogLevel.INFO
+) {
+
+  fun trace(message: () -> String?) {
+    if (level.ordinal <= LogLevel.TRACE.ordinal) {
+      println("TRACE: ${message()}")
+    }
+  }
+
+  fun debug(message: () -> String?) {
+    if (level.ordinal <= LogLevel.DEBUG.ordinal) {
+      println("DEBUG: ${message()}")
+    }
+  }
+
+  fun info(message: () -> String?) {
+    if (level.ordinal <= LogLevel.INFO.ordinal) {
+      println("INFO: ${message()}")
+    }
+  }
+
+  fun warn(e: Throwable? = null, message: () -> String?) {
+    if (level.ordinal <= LogLevel.WARN.ordinal) {
+      println("WARN: ${message()}")
+      e?.printStackTrace()
+    }
+  }
+
+  fun error(e: Throwable? = null, message: () -> String?) {
+    if (level.ordinal <= LogLevel.ERROR.ordinal) {
+      println("ERROR: ${message()}")
+      e?.printStackTrace()
+    }
+  }
+
+  fun fatal(e: Throwable, message: () -> String?) {
+    println("FATAL: ${message()}")
+    e.printStackTrace()
+  }
+}