Sot 89 custom pads

[evanshultz]

Breaking apart #981.

SOT-89-3 had no datasheet so I picked http://ww1.microchip.com/downloads/en/DeviceDoc/3L_SOT-89_MB_C04-029C.pdf and updated the footprint to match.

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Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the footprint(s) you are contributing
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[evanshultz]

Regarding the body size above. I edited the comment. At #981 (comment) Rene said that the body size in the datasheet should match our footprint. I noted the governing body has the same size at #981 (comment). The part body was already changed but as I started at the top and made my way down the large number of comments in the old PR I didn't catch that earlier.

Hopefully this isn't a problem if there are wider parts that I didn't find since the existing body size is 5mm.

[poeschlr]

Thanks for this great enhancement.