[flang] Changes to enforce constraints C727 to C730 and most constraints related to attributes

The full list of constraints is C727, C728, C729, C730, C743, C755, C759, C778,
and C1543.

I added a function to tools.cpp to check to see if a symbol name is the name
of an intrinsic type.

The biggest change was to resolve-names.cpp to check to see if attributes were
either duplicated or in conflict with each other.  I changed all locations
where attributes were set to check for duplicates or conflicts.

I also added tests for all checks and annotated the tests and code with the
numbers of the constraints being tested/checked.

Original-commit: flang-compiler/f18@3f30e8a61e605b9ca6a67791469053286ae563b2
Reviewed-on: https://github.com/flang-compiler/f18/pull/1084