Examine template symbols in lookup_local_symbol

This changes lookup_local_symbol to directly examine any attached
template symbols, rather than gating this lookup on the use of C++ or
Fortran.  As mentioned in an earlier patch, these objects are not
necessarily C++-specific, and doing the search generically seems
better.

This also renames cp_lookup_symbol_imports_or_template now that the
"template" part has been removed.