add permutation unit tests

[ChuyueSun]

The old unit test does not run at all.

[NikolajBjorner]

/usr/bin/clang++ -D_EXTERNAL_RELEASE -D_MP_INTERNAL -I/home/vsts/work/1/s/build/src -I/home/vsts/work/1/s/src -Werror=odr -Werror=return-type -Werror=delete-non-virtual-dtor -Werror=overloaded-virtual -Werror=non-virtual-dtor -Werror=null-dereference -fcolor-diagnostics -O2 -g -DNDEBUG -std=gnu++17 -mfpmath=sse -msse -msse2 -Wall -MD -MT src/test/CMakeFiles/test-z3.dir/permutation.cpp.o -MF src/test/CMakeFiles/test-z3.dir/permutation.cpp.o.d -o src/test/CMakeFiles/test-z3.dir/permutation.cpp.o -c /home/vsts/work/1/s/src/test/permutation.cpp
/home/vsts/work/1/s/src/test/permutation.cpp:2:10: fatal error: 'permutation.h' file not found
#include "permutation.h"
^~~~~~~~~~~~~~~
1 error generated.

[NikolajBjorner]

the include path should be "util/permutation.h"

[NikolajBjorner]

I guess you need to include something for in permutation.cpp. The build on mac says:

../src/test/permutation.cpp:81:24: error: implicit instantiation of undefined template 'std::basic_ostringstream'
std::ostringstream out;
^
/Applications/Xcode_14.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/iosfwd:141:32: note: template is declared here
class _LIBCPP_TEMPLATE_VIS basic_ostringstream;
^
1 error generated.

[NikolajBjorner]

The unit test fails