refactor(android): read accessibility increments directly from ReadableArray

setAccessibilityIncrements was going ReadableArray -> ArrayList<Object> via
toArrayList() and then copying again into ArrayList<String> with an unchecked
(String) cast. Read strings directly via getString(i) into a presized list.
Drops the redundant intermediate allocation and the unsafe cast.

Author: pataar

package/android/src/main/java/com/reactnativecommunity/slider/ReactSliderManagerImpl.java

@@ -124,10 +124,10 @@ public static void setAccessibilityUnits(ReactSlider view, String accessibilityU
     }
 
     public static void setAccessibilityIncrements(ReactSlider view, ReadableArray accessibilityIncrements) {
-        List objectList = accessibilityIncrements.toArrayList();
-        List<String> stringList = new ArrayList<>();
-        for(Object item: objectList) {
-            stringList.add((String)item);
+        int size = accessibilityIncrements.size();
+        List<String> stringList = new ArrayList<>(size);
+        for (int i = 0; i < size; i++) {
+            stringList.add(accessibilityIncrements.getString(i));
         }
         view.setAccessibilityIncrements(stringList);
     }