Scripted alternatives for #626 (qfn-48 5x5mm and 6x6mm)

This is an alternative to #626 I mainly created it to show @Misca1234 what should be changed in the script for adding a footprint but also as a testcase as the 5x5 is quite interesting compared to other qfn footprints.

Datasheet (for easier review): https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf (drawings on page 38)

The size definitions are added in commit: https://github.com/pointhi/kicad-footprint-generator/pull/125/commits/6722aacba47ebac8b524622b9ada096a5537174d

Copper layout (thermal via versions not shown for higher resolution)

Paste layout: