MDL-76499 revealed a few problems with resource generators:
1. We were not covering with unit tests the upload of files from disk
(and here it's where the problem was).
2. There was a little of confusion between disk paths (only needed
to upload files) and file_area paths (the generator only creates
or uploads files to the root directory of the file area.
3. It was possible to request the upload of a file to the generator
without that file effectively existing.
This commit fixes those points and covers 99% of the generator code.
Replace steps that manually add resource instances via the UI and use
Behat generators. This improves the speed of the Behat test runs.
Co-authored-by: David Woloszyn <david.woloszyn@moodle.com>
Eloy Lafuente (stronk7)