Remove top-level tests and test data

[sajith]

Issue is #182. Changes:

• Removes the top-level tests/test_Solver.py, because it really is a test of PCE. I will move that test to pce (or at least parts of it that do not overlap with the existing pce tests). The issue to track this is Move some sdx-controller tests here pce#132.
• Remove associated test data.
• Remove top level samples directory, because the topology files are broken.

Also see #168.

[coveralls]

coverage: 36.146%. remained the same when pulling 62176eb on 182.consolidate-tests-and-topologies into 3c3fbf7 on main.

[YufengXin]

These tests are largely the same as those in PCE. The purpose originally was to let Cong to test the PCE APIs within the SDX-Controller before integrating into the controller code in confidence. So it's Cong's call @congwang09.

[sajith]

That makes sense as an interim measure. However if we keep the tests here, it is going to duplicate the code that's been already moved to pce (in atlanticwave-sdx/pce#134). That is less than ideal.

If we really don't mind duplicating tests, we should still remove the static JSON files from here and use the ones from pce once atlanticwave-sdx/pce#139 is merged. I will update this PR based on Cong's feedback.

[congwang09]

I think this is fine. I'll use the tests in pce for testing. And we can avoid. inconsistency between the two repo.