fix solve in exp time with c orrectness output result to satisfy all 2

[ajfAfg]

Motivation

Cases were found that could not be handled by modifying #27.

8> G1 = #{1 => [2], 2 => [3], 3 => [4,5], 4 => [], 5 => [], 6 => [5], 7 => [4,8], 8 => [], 9 => [10], 10 => [8,11], 11 => [12,13], 12 => [], 13 => [], 14 => [2,15], 15 => [12], 16 => [13,15]}.
#{1 => [2],
  2 => [3],
  3 => [4,5],
  4 => [],5 => [],
  6 => [5],
  7 => [4,8],
  8 => [],9 => "\n",10 => "\b\v",11 => "\f\r",12 => [],
  13 => [],
  14 => [2,15],
  15 => "\f",
  16 => [13,15]}
10> all_local_minimum_vertex_splitters_solver:solve_in_polynomial_time_wit
hout_correctness( dependency_digraph:from_dependency_graph(G1) ).
[[4],[5],"\b","\f","\f\r"]
11> all_local_minimum_vertex_splitters_solver:solve_in_exp_time_with_corre
ctness( dependency_digraph:from_dependency_graph(G1) ).          
[[4,8],[5]]

In the above example, [4, 12, 15] is also a local minimum vertex splitter, but it is not included in the calculation result.

Approach

Calculate all the combinations in a straightforward manner.