Fix pasting an image into an edited message instead of sending a new copy

[UnreachableCode]

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Description

I think when the edit message feature was added, the ability to paste an image into the editing message was overlooked. Worth noting that this same bug also exists in the iOS application. I will not be fixing the iOS bug at this time.

For the fix, I've added the edit message ID into ConversationFragment.sendPreUploadMediaMessage(...) for the messageToEdit parameter. This is how it's done in the regular text send. I tested it with several messages in a chat and it now edits the existing message instead of sending a fresh one.