[NUI][API11] Remove DynamicProperty callback if URL changed + Make more thread safe...

[NUI][API11] Remove DynamicProperty callback if URL changed + Make more thread safe enough

Let us remove DynamicProperty callbacks if URL changes.
So far, we discard the callbacks if visual was changed.
But, the callbacks, which NUI stored, were not removed and remained alive
whenever we changed the URL.

Let us ensure their removal when URL changed (~= Visual Changed)

+

To avoid race condition, let we add lock feature before change `InternalSavedDynamicPropertyCallbacks`
(Since we can access this dictionary from various threads.) and make `weakReferencesOfLottie` as `ConcurrentDictionary` type.

Note : Since we need to iterate by `InternalSavedDynamicPropertyCallbacks.Keys` we need to use lock,
instead of `ConcurrentDictionary`.

TODO : There are some cases where we don't want to destroy registered callbacks. They will remain active in the future.
We make relative sample at `LottieAnimationViewDynamicPropertyTest.cs`. Let we pass `Test4` case show dynmaic property well.

Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>