add variant of HTSSOP-44 with exposed pad, used by DRV8412.

Hi,

this is an variation of the existing footprint "HTSSOP-44_6.1x14mm_P0.635mm_TopEP4.14x7.01mm" adding an exposed pad for use with DRV8412 (kicad-symbols!4271 (comment 1750899923))

Screenshot:

Datasheet: https://www.ti.com/lit/pdf/pptd165

Land pattern:

check_footprint.py still finds the following KLC violations:

Checking footprint 'HTSSOP-44_6.1x14mm_P0.635mm_EP4.31x8.26mm':
  Violating EC02 - (extended check)
    Pad shape checks
    Rectangular SMD pad
  Violating F6.3 - https://klc.kicad.org/footprint/f6/f6.3/
    Pad requirements for SMD footprints
    Pad(s) potentially missing layers

F6.3 is intentional here, as the big EP is used as heatsink with a solder mask window - but is it done right?

Thanks for your work!

have fun, Thomas