* Heterogenous sub-graph comparison testing

* Print index for float differences

* Disabled compare_backends_with_graphs on most backends for now. Moved to new file. Added testing of unsigned values.

* Fixed element::boolean range. Added missing include.

* Switched use of shared_ptr as parm to raw *. Moved to using namespace std in cpp. Fixed comment marker in unit_test.manifest files. Switched some EXPECT_EQ TO ASSERT_EQ. Fixed parameterized test disabling.

* Frozen naming -> serialized. Removed extraneous comments.

* Graph comparison unit test relies on CPU for reference, so only build when CPU is built.

* Reworked per backend disabling of compare_backends_with_graphs