Add: DFN: Microchip CDFN-4 packages

The other, "CDFN" packages from the DSC100x range. The 7x5 generator "DFN" YAML is already merged ( !1128 (merged)), the generated output for that is kicad-footprints!3647.

https://ww1.microchip.com/downloads/aemDocuments/documents/TCG/ProductDocuments/DataSheets/DSC1001-3-4-1.8V-3.3V-Low-Power-Precision-CMOS-Oscillators-DS20005529.pdf

As these are IPC generations, the lands don't 100% agree with DS figures.

2x2.5:

2.5x3.2:

3.2x5:

3D fitups using the UltraLibrarian 3D models:

Notes:

• The 3.2x5 is physically a pullback package per the DS, but Microchip recommends a protruding pad like a normal D/QFN. The UL 3D model doesn't show this.

Generated ouptut footprint MR: kicad-footprints!3664