Built-in test for special cases

[nrueh]

Add built-in tests for special cases like UNSAT and empty model.

For example like this:

UNSAT: Assert(All(), False_)
Empty Model: Assert(All(), SubsetOf(set()))

[nrueh]

Maybe there is a better way to implement the UNSAT.

This way Assert(All(), False_) does not give a clintest error when the test fails but a python error:

Traceback (most recent call last):
  File "/Users/nicolasruhling/projects/coom-solver/tests/test_sanity_checks.py", line 97, in test_empty_combinations
    run_test(TEST_UNSAT, program=program_unsat)
  File "/Users/nicolasruhling/projects/coom-solver/tests/__init__.py", line 47, in run_test
    solver.solve(test_copy)
  File "/Users/nicolasruhling/projects/coom-solver/tests/__init__.py", line 135, in solve
    self.__application.main(control=ctl, files=self.__files)  # type: ignore
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/nicolasruhling/projects/coom-solver/src/coomsolver/application.py", line 153, in main
    control.solve()
  File "/Users/nicolasruhling/projects/coom-solver/tests/__init__.py", line 101, in solve
    self._ctl.solve(
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clingo/control.py", line 848, in solve
    _c_call(
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clingo/_internal.py", line 44, in _c_call
    _handle_error(c_fun(*args, p_ret), handler)
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clingo/_internal.py", line 71, in _handle_error
    raise handler.error[0](handler.error[1]).with_traceback(handler.error[2])
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clingo/control.py", line 121, in _pyclingo_solve_event_callback
    goon[0] = handler.on_model(_ffi.cast("clingo_model_t*", event))
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clingo/control.py", line 93, in on_model
    ret = self._on_model(Model(m))
          ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/nicolasruhling/projects/coom-solver/tests/__init__.py", line 63, in f
    on_test(*args)
  File "/Users/nicolasruhling/projects/coom-solver/.nox/test-3-11/lib/python3.11/site-packages/clintest/test.py", line 363, in on_model
    self.__quantifier.consume(self.__assertion.holds_for(model))
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: False_.holds_for() missing 1 required positional argument: 'model'