Support for incremental bit-blasting with CaDiCaL (#3006)

Support for incremental bit-blasting with CaDiCaL (#3006)

This commit adds support for eager bit-blasting with CaDiCaL on
incremental benchmarks. Since not all CaDiCaL versions support
incremental solving, the commit adds a CMake check that checks whether
`CaDiCaL::Solver::assume()` exists.

Note: The check uses `check_cxx_source_compiles`, which is not very
elegant but I could not find a better solution (e.g.
`check_cxx_symbol_exists()` does not seem to support methods in classes
and `check_struct_has_member()` only seems to support data members).