Add the ability to open message context in media view

[SystemKeeper]

When swiping through images in the media view, it is not possible to jump to the message that belongs to the image. We could add a way to show the message in the ContextChatViewController (much like it is done in the shared items dialog) to get some information about the message. Jumping to the message might not be possible, since it depends on if the message was loaded or not.