Move activity creation to data generators. Only fixing those
tests failing due to removing usemodchooser preference.

This commit removes activity chooser user preference and
course preference page. Separate dropdowns to activity and
resource is also removed.

The define_after_data method was looking for a required_param
when it should have been an optional parameter. This was causing
error messages when creating a new datetime field.

A HTTP HEAD request is required to get the image filesize.
The remaining data can be obtained from existing calls to
the Flickr API.

Huong Nguyen authored Apr 01, 2021 and Huong Nguyen committed Apr 29, 2021

Interacts badly with double-submit protection, and not all uploads protected