[6.1] Expand useGlobal to also use plugin parameters

[Ruud68]

Pull Request for Issue # -.

Summary of Changes

In form xml files you can add useglobal="true", this will then extend the field to show the value for the field in the matching component options.

This PR extends the useglobal to not only use the component options but also a plugins options.

This will create the possibility to have the same functionality it had but then for (global) plugin parameters.

This is a POC on the 'text' field to see if there is interest in this change, if so I can further extend it to the other fields that have the useglobal functionality:

• MailtemplateLayoutField
• ComponentLayoutField
• ListField
• NumberField
• PluginsField

Testing Instructions

on a formfield you can now have the following useglobal settings:

• useglobal="true": this will take the configured field value from the component
• useglobal="plg_system_xyz": this will take the configured value from the plugin with type 'system' and name 'xyz'

Actual result BEFORE applying this Pull Request

The text field would show empty

Expected result AFTER applying this Pull Request

The textfield will show 'Use Global (abc)' where abc is the value of the field in the plugin configuration

Link to documentations

Please select:

• Documentation link for docs.joomla.org: https://manual.joomla.org/docs/general-concepts/forms-fields/standard-fields/text/

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed