Support Opening the Scheduled Document files

[Sagar0-0]

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Description

1. Support Opening documents for Scheduled messages as there is no preview available for Documents if they are scheduled.

Why Only Documents?

1. For Images/Video, there is a thumbnail present that indicates which item will be sent. I want to support opening these also, but Deleting the message from MediaPreview disturbs the scheduled messages. "Delete for Me" removes the scheduled message. And "Delte for Everyone" will mark the scheduled message as delete and it will still be scheduled and will be sent". And, Scheduled Sheet won't be updated after any actions from MediaPreview Activity. More refactoring will be required for supporting these.
2. For Scheduled audio, I have already raised Fix Audio Play from Scheduled Messages #13951
3. For docs, there is no preview available when scheduled, so user might not know which file they have sent.