Use mathematical modulo implementation for calculations (#616)

See documentation (%/rem, mod) for differences.

Example for "issue" that occurred:
mathematical: -4 % 6 = 2 (expected)
kotlin: -4 % 6 = -4 (unexpected)

server/src/main/kotlin/suwayomi/tachidesk/util/HAScheduler.kt

@@ -62,7 +62,7 @@ class HATask(id: String, val interval: Long, execute: () -> Unit, val timerTask:
 
     private fun getElapsedTimeOfCurrentInterval(): Long {
         val timeSinceFirstExecution = System.currentTimeMillis() - firstExecutionTime
-        return timeSinceFirstExecution % interval
+        return timeSinceFirstExecution.mod(interval)
     }
 
     override fun getLastExecutionTime(): Long {