DIP: Add a declarative YAML-based generator for DIPs

This adds a YAML-based DIP generator, and then uses it to implement a range of JEDEC MS-015 side-brazed CERDIPs (Ax variants - 0.300") (which are needed for PIC12s).

MS-015: https://www.jedec.org/system/files/docs/Ms-015a.pdf

Microchip has a windowed package, but at least for now this isn't directly supported in the generator, and the main dimensions are otherwise in-tolerance (or extremely close to it, in the case of C)

Minor changes are made to the underlying makeDIP function:

• Rotate ref des to vertical when needed, which is usually (as a separate commit)
• Add datasheet field (as a separate commit)

Detail of the 8-pin package:

Overview (all parts have all 4 variants):

• I have used the same values for long pads and socket offsets as for normal DIPs.

This is a fit-up with a 3D model of a PIC12 -JW package, but it's clearly not 100% accurate, as there's no window for a start:

DIP8_300MC_MCH.step

Generated FP MR: kicad-footprints!3444 (merged)