Summary

Previously, automatic resource download was handled on component mount by checking the body of this.state.note. However at this point, this.state.note is not set (setState has been called, but this doesn't seem to set this.state.note immediately).

This pull request moves the automatic resource download check to componentDidUpdate, when state.isLoading goes from false to true. At present, isLoading is set to true initially, then set to false after loading a note.

This pull request should fix #11134.

Testing plan

This pull request adds an automated test.

Additionally, it has been tested manually on web (Chromium) by:

1. Attaching a new resource to a note on the desktop app.
2. Syncing the desktop app.
3. Switching to the mobile app (web, attachment download behavior set to "auto").
4. Syncing the mobile app.
5. Opening the modified note.
6. Verifying that the resource icon is shown as an hourglass.
7. Verifying that the resource hourglass icon is replaced with the resource.