~ruther/vhdl-spi-2

ref: 94410b0e9f2ca2e0fdf37df9c565150784b99655 vhdl-spi-2/hdl_spi/tests d---------
feat: tests for multiple transmissions, rx lost
chore: add ghdl support vhdl2008 arg
feat: add first basic test
chore: few updates
feat: implement initial hdl_spi