This issue resolves the following user story:

1. As a teacher, I need my resources shared to MoodleNet asynchronously, so that I do not need to wait for the process to complete before moving on to other tasks.

This cannot be completed until after the share history is implemented and includes send status, otherwise teachers will have no way to determine the state of their upload from the LMS.

Backend requirements

1. Move the existing packaging and sending process into an ad-hoc task.
2. Update the status in the share history as appropriate (in progress, sent, failed).

Frontend requirements

1. Update the second and third modal screens to reflect the changes (eg linking to the share history instead of MoodleNet drafts, since the file will not be uploaded when reaching that screen). Prototype/designs for this are still WIP, and will need to be completed before the issue is commenced.

Out of scope

1. Any changes to the interaction with MoodleNet's API (it still uses the existing API, which does not support resume etc).
2.  Validating connection before attempting to send (implemented by MDL-77297).
3. Any "retry" facility in the frontend, which can be implemented in a follow up if necessary.