Dfn generator cleanup

This MR is purely are cleanup of the QFN/DFN generator. This MR does not change functionality or fix bugs.

I made the following changes:

• Removed unused variables
• Cleaned up white spaces
• Fixed indentation
• Removed redundant parenthesis
• Also removed mN = params['model_name'] and rot = params['rotation'] both from the source code and the yaml file (Edit: This was an error, reverted)
• Removed unused import
• Replaced format string with f-string for better readability
• Replaced singleton-comparisons
• Added line breaks to limit the maximum line length to <=120 characters
• Removed duplicate key body_color_key from yaml file

These changes were all made in separate commits to make them easier to review.