Separated manager and subordinate drivers

Other clean up and changes

src/axi/axi_pkg.sv

@@ -9,6 +9,8 @@ package axi_pkg;
 
     // UVM components
     `include "axi_driver.sv"
+    `include "axi_subordinate_driver.sv"
+    `include "axi_manager_driver.sv"
     `include "axi_monitor.sv"
     `include "axi_agent.sv"
 endpackage