[BUG] go infinite not properly obeyed

[dannyhammer]

Describe the bug
According to the UCI Spec, a go [infinite] command should cause the engine to only exit the search when the stop command is sent. So, even if the search concludes, bestmove should not be sent until stop is received.

An example FEN that is trivial to search would be this: 8/8/8/8/q7/1k6/8/K7 w - - 0 1, which has only 1 legal move available (a1b1).

Expected behavior
When go [infinite] is sent, bestmove should not be printed until stop is received.

Additional context
Heimdall handles this by sleeping until stop is received.