major interface conversion update

- module instances with modport bindings are now inlined
- support for modports in generate loops
- support for generic interfaces
- implied modport instance propagation
- add error message for interface instances missing port list

test/basic/interface_shadow.sv

@@ -0,0 +1,32 @@
+typedef struct packed { logic x; } T;
+
+interface Interface;
+    integer x;
+    function z;
+        input x;
+        z = ~x;
+    endfunction
+endinterface
+
+module Module(interface y);
+    function z;
+        input T y;
+        z = y.x;
+    endfunction
+    integer x = 0;
+    initial begin
+        #1;
+        $display("x = %b", x);
+        $display("z(x) = %b", z(x));
+        $display("y.x = %b", y.x);
+        $display("y.z(x) = %b", y.z(x));
+        $display("y.z(y.x) = %b", y.z(y.x));
+        $display("y.z(z(y.x)) = %b", y.z(z(y.x)));
+    end
+endmodule
+
+module top;
+    Interface x();
+    initial x.x = 1;
+    Module y(x);
+endmodule