Add: Regulator_Switching: LT8306
This adds the LT8306 switching regulator.
https://www.analog.com/media/en/technical-documentation/data-sheets/lt8306.pdf
(R_FB is subscript in the pin table, I chose to use that)
Schematic example per the DS application diagram:
I chose to add one 100 mil grid between R_fb and GATE over the LT8303, as it allows the gate connection to be straight without crowding the MOSFET drain (I like it when there's a litte green bit if possible)