Added testbench for instruction classifier and fixed compilation errors. Should be fine to synthesise but icarus does not like the constant bit extraction in the always_comb block for some reason.

modules/instruction_classifier.sv

@@ -1,4 +1,4 @@
-module instruction_classifier(input logic op[5:0],
+module instruction_classifier(input logic[5:0] op,
     output logic[0:0] R, output logic[0:0] B1, output logic[0:0] J,
     output logic[0:0] B2, output logic[0:0] I, output logic[0:0] F,
     output logic[0:0] M);