Fix android build errors with RN 0.71

- Add redundant handling for missing permission exceptions. Existing checks work but
  do not satisfy lint, so this is the only way to resolve #646

- Upgrade gradle to maximum compatible version (3.6.4) to satisfy new minimum (3.2.0)

- Use AudioManager.MODE_NORMAL constant explicitly (instead of the equivalent value of
  "0" currently being used) to satisfy lint

- Replace deprecated WindowManager.LayoutParams constants with Activity API methods
  when using Android SDK v27+

Author: ramijarrar

android/build.gradle

@@ -5,7 +5,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
+        classpath 'com.android.tools.build:gradle:3.6.4'
     }
 }
 

android/src/main/java/io/wazo/callkeep/RNCallKeepModule.java

@@ -512,7 +512,9 @@ public void startCall(String uuid, String number, String callerName, boolean has
 
         Log.d(TAG, "[RNCallKeepModule] startCall, uuid: " + uuid);
         this.listenToNativeCallsState();
-        telecomManager.placeCall(uri, extras);
+        try {
+            telecomManager.placeCall(uri, extras);
+        } catch (SecurityException ignored) {}
     }
 
     @ReactMethod
@@ -530,7 +532,7 @@ public void endCall(String uuid) {
         }
         Context context = this.getAppContext();
         AudioManager audioManager = (AudioManager) context.getSystemService(context.AUDIO_SERVICE);
-        audioManager.setMode(0);
+        audioManager.setMode(AudioManager.MODE_NORMAL);
         conn.onDisconnect();
         this.stopListenToNativeCallsState();
         this.hasActiveCall = false;
@@ -673,7 +675,11 @@ public void checkDefaultPhoneAccount(Promise promise) {
         }
 
         boolean hasSim = telephonyManager.getSimState() != TelephonyManager.SIM_STATE_ABSENT;
-        boolean hasDefaultAccount = telecomManager.getDefaultOutgoingPhoneAccount("tel") != null;
+
+        boolean hasDefaultAccount = false;
+        try {
+            hasDefaultAccount = telecomManager.getDefaultOutgoingPhoneAccount("tel") != null;
+        } catch (SecurityException ignored) {}
 
         promise.resolve(!hasSim || hasDefaultAccount);
     }
@@ -1078,14 +1084,20 @@ public void backToForeground() {
         if (isOpened) {
             focusIntent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
             activity.startActivity(focusIntent);
-        } else {
-            focusIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK +
-                    WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED +
-                    WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD +
-                    WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
+            return;
+        }
 
-            getReactApplicationContext().startActivity(focusIntent);
+        focusIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
+            activity.setShowWhenLocked(true);
+            activity.setTurnScreenOn(true);
+        } else {
+            activity.getWindow().addFlags(
+                WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED +
+                WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
         }
+
+        getReactApplicationContext().startActivity(focusIntent);
     }
 
     public static void onRequestPermissionsResult(int requestCode, String[] grantedPermissions, int[] grantResults) {