ENYO-2505: Persistent item’s incomplete swipe action is completed on a subsequent swipe

Issue
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For persistent swipeable items, an incomplete swipe will be completed on a subsequent swipe (i.e. swipe and drag to scroll). This is caused by the `persistentItemVisible` flag being set to `true` regardless of the swipe completion status. 

Fix
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The `persistentItemVisible` flag is now only set if the swipe is complete. The choice to make a change here, as opposed to calling `setPersistSwipeableItem(false)` in the `backOutSwipe` method, is that this change is agnostic to how persistent items are implemented (currently `setPersistSwipeableItem(true)` needs to be called for each item via the `setupSwipeItem` handler). For example, if the implementation were to change such that the `persistSwipeableItem` flag on the `List` was not treated as temporary, then `setPersistSwipeableItem(false)` in `backOutSwipe` would eat this value.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>