Add Texas_USON-6_1x1.45mm_P0.5mm_SMD

Datasheet: https://www.ti.com/lit/ds/symlink/sn74auc1g04.pdf#page=24

Used in many of the components in TI's Little Logic product line.

Solder mask defined, so originally scripted and then modified by hand to adjust mask settings. Solder mask expansion set in footprint properties instead of pad properties so it applies to all pads at once.