Added DMT3020LDV-x dual fet

Added atomic symbol for kicad-footprints!3152 (merged) footprint as discussed in !3895 (merged)

This is a copy of the s1g1s2g2d2d1 symbol from device, with p6 renamed to p7 to match the footprint. Also added datasheet to meta data (Will this be the norm in >=8.0?)

I'm unsure about the footprint filter. Any feedback on that'd be nice 🙂

Datasheet: https://www.diodes.com/assets/Datasheets/DMT3020LDV.pdf