Modify ipc_2terminal_chip_molded_generator.py to add custom_name_format support

Update of: !491 (closed)

I needed to generate a footprint for a ceramic chip antenna, like this one: https://www.johansontechnology.com/datasheets/2450AT18A100/2450AT18A100.pdf

I thought it would be great to use ipc_2terminal_chip_molded_generator.py for this, but it doesn't allow custom name formats.

This patch allows to add a custom_name_format field, and if used, it allows to use a description field in the params.

Using this, I can generate footprints for the above antenna, with correct naming.