This commit adds support to description field for presets:
- For plugin presets, description will be stored in the module_help
string in lang files.
- For saved presets, a new element, <description>, has been added
to the preset.xml file, to include this information.
A new field has been added to the "Save as preset" modal, to let users
define description (which is empty by default, to support pre-existing
presets that won't have it).
Apart from that, the "Save as preset" workflow has been slightly improved,
following the Product UX/UX suggestions to hide the checkbox to overwrite
the preset by default and show it only if the user tries to save a preset
with an existing name.
This activity currently supports two different preset types:
- Datapreset plugins, that can be installed copying them to the
mod/data/preset folder.
- Presets saved manually by users.
This commit adds an attribute to the presets to mark them, in order
to identify them later (because, for instance, the plugins can't be
removed).
Apart from that, the methods in lib.php, involved with this issue, have
been deprecated. New methods have been implemented in the manager class,
covering them with PHPUnit tests.
