Reorganize classes

- Move base classes to its own package
- Move most logic out of MagiskActivity to MainActivity

app/src/main/java/com/topjohnwu/magisk/model/events/EventHandler.kt

@@ -15,4 +15,11 @@ internal interface EventHandler {
      * the way how you handle them.
      */
     fun onSimpleEventDispatched(event: Int) {}
+
+    val viewEventObserver get() = ViewEventObserver {
+        onEventDispatched(it)
+        if (it is SimpleViewEvent) {
+            onSimpleEventDispatched(it.event)
+        }
+    }
 }

app/src/main/java/com/topjohnwu/magisk/model/events/RxEvents.kt

@@ -1,10 +1,10 @@
 package com.topjohnwu.magisk.model.events
 
-import com.topjohnwu.magisk.utils.RxBus
 import com.topjohnwu.magisk.model.entity.MagiskPolicy
 import com.topjohnwu.magisk.model.entity.recycler.HideProcessRvItem
 import com.topjohnwu.magisk.model.entity.recycler.ModuleRvItem
 import com.topjohnwu.magisk.model.entity.recycler.PolicyRvItem
+import com.topjohnwu.magisk.utils.RxBus
 
 class HideProcessEvent(val item: HideProcessRvItem) : RxBus.Event
 

app/src/main/java/com/topjohnwu/magisk/model/events/SimpleViewEvent.kt

@@ -1,7 +1,5 @@
 package com.topjohnwu.magisk.model.events
 
-import com.topjohnwu.magisk.model.events.ViewEvent
-
 class SimpleViewEvent(
     val event: Int
 ) : ViewEvent()

app/src/main/java/com/topjohnwu/magisk/model/events/SnackbarEvent.kt

@@ -3,7 +3,6 @@ package com.topjohnwu.magisk.model.events
 import android.content.Context
 import androidx.annotation.StringRes
 import com.google.android.material.snackbar.Snackbar
-import com.topjohnwu.magisk.model.events.ViewEvent
 
 class SnackbarEvent private constructor(
     @StringRes private val messageRes: Int,