Add progressbar property to indicator result

[ecarreras]

This pull request adds support for a new progressbar attribute to indicator graphs, allowing them to display a progress bar based on the value and total. The implementation includes updates to the IndicatorGraph class to parse and expose the new attribute, modifies the processing logic to handle progress bar display, and adds comprehensive tests to verify the new behavior.

Indicator graph enhancements:

• Added support for a progressbar attribute in the IndicatorGraph class, including parsing the attribute from XML and exposing it as a property. [1] [2]
• Updated the process method to include the progressbar key in the result when applicable, and to ensure the percent value is included when either progressbar or showPercent is true.

Testing improvements:

• Expanded the test suite in graph_spec.py to cover the new progressbar attribute, including its interaction with the percent value and different combinations of attributes.

Related

• https://github.com/gisce/webclient/issues/2656