Added all Testbenches to Modelsim and confirmed working operation

ModelSim/tests.sv

@@ -0,0 +1,6 @@
+`include "tests/seven_seg_tb.sv"
+`include "tests/lu_tb.sv"
+`include "tests/asu_tb.sv"
+`include "tests/instruction_classifier_tb.sv"
+`include "tests/shifter_tb.sv"
+`include "tests/alu_tb.sv"