Add dynamic expression button for substitution line and new converter features

• Introduced a button to dynamically set the expression in the substitution line.

• The feature is available for converters of type "Odoo template", "Odoo template + Evaluation", and "Field".

• Added functionality to visualize how to define each converter, displaying a placeholder (example) for each converter type.

• The code has been designed to ease the integration of additional converters in the future.

• Refactored the code to improve performance and stability.

• Add missing python-magic requirement for package