[4.0] Implementing display of fieldset descriptions for fieldset children

[infograf768]

Pull Request for Issues #30433 & #30431

Summary of Changes

Added the possibility to display fieldsets description for children (and parent when there are children)

Testing Instructions

Structure of a xml with children fieldsets

<fieldset name="filtering" label="MOD_ARTICLES_CATEGORY_FIELD_GROUP_FILTERING_LABEL" description="Top most description">

<fieldset name="filtering_child1" label="Child 1" description="Child description 1">
[some fields]
</fieldset>
<fieldset name="filtering_child2" label="Child 2" description="Child description 2">
[the remaining fields]
</fieldset>

</fieldset>

For example, replace the file modules/mod_articles_category/mod_articles_category.xml where I have made such a structure.
with this one (unzip first)
mod_articles_category.xml.zip

Test, then patch and run NPM as we have a small scss change.

Actual result BEFORE applying this Pull Request

Expected result AFTER applying this Pull Request

@obuisard
Please test and add your test result on https://issues.joomla.org/tracker/joomla-cms/30450

[obuisard]

I have tested this item ✅ successfully on 151b0ac

Perfect, thank you!

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[Quy]

Suggested change

	if (isset($fieldSet->description) && trim($fieldSet->description))
	if (!empty($fieldSet->description))

[infograf768]

@Bakual
See #3048

EDIT: in fact that code is much much older...

Any reason to use
if (isset($fieldSet->description) && trim($fieldSet->description))
instead of @Quy proposal above
if (!empty($fieldSet->description))

[Bakual]

I haven't changed the code itself in that old PR, I just moved it to a different place. So I wasn't thinking about why the trim is there.

There would be a small difference between the code, that is when the description holds only a whitespace. The first line wouldn't show it (because trim removes the space), the second line would show it.

Personally, I would go with !empty, I think we can live with the difference in behavior.

[infograf768]

@Quy @obuisard @richard67
Modifs done. Can be tested again.

[Quy]

I have tested this item ✅ successfully on 83c9d5b

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[obuisard]

I have tested this item ✅ successfully on 83c9d5b

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[infograf768]

Back to RTC

Appveyor failure is unrelated.

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[infograf768]

Took off an extraneous new line at the end of _alerts.scss to force rebuild to solve appveyor failure to run.
No change for tests and RTC