Support for Android Tablets & Foldable (#7025)

* Add Support for Android tablets & foldables

* add tablet and book posture

* Regenerate disposed observable on WindowInfoTracker

android/app/src/main/java/com/mattermost/rnbeta/SplitViewModule.kt

@@ -0,0 +1,73 @@
+package com.mattermost.rnbeta
+
+import com.facebook.react.bridge.*
+import com.facebook.react.modules.core.DeviceEventManagerModule.RCTDeviceEventEmitter
+import com.learnium.RNDeviceInfo.resolver.DeviceTypeResolver
+
+class SplitViewModule(private var reactContext: ReactApplicationContext) : ReactContextBaseJavaModule(reactContext) {
+    private var isDeviceFolded: Boolean = false
+    private var listenerCount = 0
+
+    companion object {
+        private var instance: SplitViewModule? = null
+
+        fun getInstance(reactContext: ReactApplicationContext): SplitViewModule {
+            if (instance == null) {
+                instance = SplitViewModule(reactContext)
+            } else {
+                instance!!.reactContext = reactContext
+            }
+
+            return instance!!
+        }
+
+        fun getInstance(): SplitViewModule? {
+            return instance
+        }
+    }
+
+
+    override fun getName() = "SplitView"
+
+    fun sendEvent(eventName: String,
+                  params: WritableMap?) {
+        reactContext
+                .getJSModule(RCTDeviceEventEmitter::class.java)
+                .emit(eventName, params)
+    }
+
+    private fun getSplitViewResults(folded: Boolean) : WritableMap? {
+        if (currentActivity != null) {
+            val deviceResolver = DeviceTypeResolver(this.reactContext)
+            val map = Arguments.createMap()
+            map.putBoolean("isSplitView", currentActivity!!.isInMultiWindowMode || folded)
+            map.putBoolean("isTablet", deviceResolver.isTablet)
+            return map
+        }
+
+        return null
+    }
+
+    fun setDeviceFolded(folded: Boolean) {
+        val map = getSplitViewResults(folded)
+        if (listenerCount > 0 && isDeviceFolded != folded) {
+            sendEvent("SplitViewChanged", map)
+        }
+        isDeviceFolded = folded
+    }
+
+    @ReactMethod
+    fun isRunningInSplitView(promise: Promise) {
+        promise.resolve(getSplitViewResults(isDeviceFolded))
+    }
+
+    @ReactMethod
+    fun addListener(eventName: String) {
+        listenerCount += 1
+    }
+
+    @ReactMethod
+    fun removeListeners(count: Int) {
+        listenerCount -= count
+    }
+}