[Unit Tests] Fix shell test for Editline (#7117)

[Unit Tests] Fix shell test for Editline (#7117)

When using --editline, our interactive_shell_black unit test was not
working because the unit test was redirecting std::cin and std::cout
to std::stringstreams, which does not work with Editline. This commit
refactors our InteractiveShell class to explicitly take the input and
output streams as arguments, which fixes the issue because we do not use
Editline for input streams that are not std::cin. Additionally, the
commit updates the unit test to use SMT-LIB syntax instead of the
deprecated CVC language.