add internal fpga voltage sensor to unb2_minimal

boards/uniboard2/libraries/unb2_board/hdllib.cfg

boards/uniboard2/libraries/unb2_board/quartus/unb2_board.qsf

...iboard2/libraries/unb2_board/src/vhdl/ctrl_unb2_board.vhd

...ard2/libraries/unb2_board/src/vhdl/mms_unb2_fpga_sens.vhd

...raries/unb2_board/src/vhdl/unb2_board_peripherals_pkg.vhd

...ard2/libraries/unb2_board/src/vhdl/unb2_fpga_sens_reg.vhd