Currently, in `ChatInput.vue` we call `upload.abort()` which removes the event listeners, which are never added back. This effectively permanently disable uploads if the user navigates away to Settings or any other non-chat pages, and back.
Moves the binding to `mounted()` so that they're properly rebound when a chat window is in view, and also adds an `unmounted()` for clarity.
This should also fix an edge case if the page opens up on a non-chat page and there was never a ChatInput to unbind it, such as login page or add network pages.
