[flang] Semantic check for C708

[flang] Semantic check for C708

An entity declared with the CLASS keyword shall be a dummy argument or
have the ALLOCATABLE or POINTER attribute.

Implementing this check revealed a problem in the test resolve44.cpp.
It also showed that we were doing semantic checking on the entities
created by the compiler for LOCAL and LOCAL_INIT locality-specs.  So I
changed the creation of symbols associated with LOCAL and LOCAL_INIT
locality-specs to be host associated with the outer symbol rather than
new object entities.  In the process, I also changed things so that the
`parser::Name` associated with the newly created symbols was set to the
symbol rather than being set to nullptr.

Original-commit: flang-compiler/f18@5dd0b0bbe811a908374b2907bb38c75ca76127d2
Reviewed-on: https://github.com/flang-compiler/f18/pull/981