Disallow renaming of UnsupportedFortranTypes in `symbol_table.new_symbol`

[LonelyCat124]

Ideally we shouldn't allow renaming (and should fail) of UnsupportedFortranTypes, since they specify the type in their string body. However this currently fails because the common block creation in the fparser2 frontend then fails.

We should fix this in the future.

[sergisiso]

This would also be solved with #2137 which attempts to decouple the symbol name from the unsupported type, but it is still unclear if we can do it.

[sergisiso]

new_symbol should also be careful with "RoutineSymbols" as renaming them can break the caller<->callee expectations