[android] Add option for scrollable top tabs (#669)

android/app/src/main/java/com/reactnativenavigation/params/StyleParams.java

     public Color selectedTopTabIconColor;
     public int selectedTopTabIndicatorHeight;
     public Color selectedTopTabIndicatorColor;
+    public boolean topTabScrollable;
 
     public Color screenBackgroundColor;
 

android/app/src/main/java/com/reactnativenavigation/params/parsers/StyleParamsParser.java

         result.selectedTopTabTextColor = getColor("selectedTopTabTextColor", getDefaultSelectedTopTabTextColor());
         result.selectedTopTabIndicatorHeight = getInt("selectedTopTabIndicatorHeight", getDefaultSelectedTopTabIndicatorHeight());
         result.selectedTopTabIndicatorColor = getColor("selectedTopTabIndicatorColor", getDefaultSelectedTopTabIndicatorColor());
+        result.topTabScrollable = getBoolean("topTabScrollable", getDefaultTopTabScrollable());
 
         result.screenBackgroundColor = getColor("screenBackgroundColor", getDefaultScreenBackgroundColor());
 
         return AppStyle.appStyle == null ? new StyleParams.Color() : AppStyle.appStyle.topTabTextColor;
     }
 
+    private boolean getDefaultTopTabScrollable() {
+        return AppStyle.appStyle != null && AppStyle.appStyle.topTabScrollable;
+    }
+
     private StyleParams.Color getDefaultTopTabIconColor() {
         return AppStyle.appStyle == null ? new StyleParams.Color() : AppStyle.appStyle.topTabIconColor;
     }

android/app/src/main/java/com/reactnativenavigation/views/TopBar.java

         }
         topTabs.setTopTabsTextColor(style);
         topTabs.setSelectedTabIndicatorStyle(style);
+        topTabs.setScrollable(style);
     }
 
     public void showContextualMenu(final ContextualMenuParams params, StyleParams styleParams, Callback onButtonClicked) {

android/app/src/main/java/com/reactnativenavigation/views/TopTabs.java

         setTabTextColors(tabTextColor, selectedTabColor);
     }
 
+    void setScrollable(StyleParams style) {
+        if (style.topTabScrollable) {
+            setTabMode(TabLayout.MODE_SCROLLABLE);
+        } else {
+            setTabMode(TabLayout.MODE_FIXED);
+        }
+    }
+
     public void setTopTabsIconColor(StyleParams style) {
         new TopTabsIconColorHelper(this, style).colorIcons(getSelectedIconColor(), getUnselectedIconColor());
     }

src/deprecated/platformSpecificDeprecated.android.js

     selectedTopTabTextColor: processColor(originalStyleObject.selectedTopTabTextColor),
     selectedTopTabIndicatorHeight: originalStyleObject.selectedTopTabIndicatorHeight,
     selectedTopTabIndicatorColor: processColor(originalStyleObject.selectedTopTabIndicatorColor),
-
+    topTabScrollable: originalStyleObject.topTabScollable,
     screenBackgroundColor: processColor(originalStyleObject.screenBackgroundColor),
 
     drawScreenAboveBottomTabs: !originalStyleObject.drawUnderTabBar,