[AND-145] Fix pinned message list initial loading

[VelikovPetar]

🎯 Goal

• Fixes the initial loading of the pinned messages in the PinnedMessageListController.

🛠 Implementation details

• Previously we didn't update the state.nextDate value to the current timestamp when calling the load() method - this resulted in reusing the nextDate from the INITIAL_STATE. This was wrong, as the INITIAL_STATE value is created when the PinnedMessageListController is created, and because it is part of the companion object, the same value is also used for any subsequently created instances of the controller.
  This meant that calling load on PinnedMessageListControllers which were created after the initially created controller, will use the 'old' timestamp to fetch the pinned messages, so any message pinned after the old timestamp, will not be retrieved.

• Now we ensure that the state is properly updated with the current timestamp, when calling PinnedMessageListController.load

🎨 UI Changes

Before	After
before.mp4	after.mp4

🧪 Testing

Steps to reproduce:

1. Open a channel
2. Open PinnedMessageList for the given channel
3. Go back to channel
4. Pin a new message
5. Open PinnedMessages list
6. The newly pinned message should be shown at the top of the list