Add draft tb_sdp_beamformer_output.vhd.

applications/lofar2/libraries/sdp/hdllib.cfg

...lofar2/libraries/sdp/tb/vhdl/tb_sdp_beamformer_output.vhd

...ar2/libraries/sdp/tb/vhdl/tb_tb_sdp_beamformer_output.vhd