[Bug] Imposibility of writing assert_equals test with complex attributes

[mbs-octoml]

I wanted to unit test TEPass with something like:

def test_lower_primitive():
    input_mod = tvm.parser.parse(
        """
        #[version = "0.0.5"]
        def @main(%a: Tensor[(5, 7), float32]) -> Tensor[(5, 7), float32] {
          %0 = fn(%x : Tensor[(5, 7), float32], %y : Tensor[(5, 7), float32], Primitive=1) -> Tensor[(5, 7), float32] { 
            add(%x, %y)
          };
          %0(%a, %a)  
        }      
        """,
        "from_string", None, None,
    )

    actual_mod = transform(input_mod)
    expected_mod = tvm.parser.parse(
       """
        #[version = "0.0.5"]
        def @main(%a: Tensor[(5, 7), float32]) -> Tensor[(5, 7), float32] {
          %0 = (%a, %a);
          call_lowered(@test_fused_add, %0, metadata={relay_attrs={Primitive=1},all_prim_fn_vars=[@test_fused_add]})
        }
       def @test_fused_add(...) { ... }
       """, "from_string", None, None)
    tvm.ir.assert_structural_equal(actual_mod, expected_mod, True)

Firstly, it's not possible to express the call_lowered metadata attributes in the form written, so it needs to be bound to a meta table entry.

    test_fused_add = actual_mod.get_global_var('test_fused_add')
    call_lowered_attrs = {
        "relay_attrs": tvm.ir.make_node("DictAttrs", Primitive=tvm.tir.IntImm("int32", 1)),
        "all_prim_fn_vars": [test_fused_add]
    }
    metadata = {
        "attrs": [call_lowered_attrs]
    }

That's ok, but the global var baund to 'test_fused_add' is not right, it needs to be the same object as created to represent the definition in the expected module.

I think we should have a structural_equal mode that compares on name_hint alone. We almost have that, but somehow in all the logic the 'map_free_vars' options got reset to False and triggered a failure.