axi: Add AXI lite width converter module and testbench

Signed-off-by: Alex Forencich <alex@alexforencich.com>

src/axi/rtl/taxi_axil_adapter.f

@@ -0,0 +1,4 @@
+taxi_axil_adapter.sv
+taxi_axil_adapter_wr.sv
+taxi_axil_adapter_rd.sv
+taxi_axil_if.sv