[flang] Allow for host association in ConvertTo(Object|Proc)Entity

[klausler]

Summary

Name resolution fails with a bogus "is not a variable" error message
when a host-associated object appears in a NAMELIST group. The root
cause is that ConvertToObjectEntity() returns false for host-associated
objects. Fix that, and also apply a similar fix to ConvertToProcEntity()
nearby.

flang/lib/Semantics/resolve-names.cpp

if (symbol.has<ObjectEntityDetails>()) {
     // nothing to do
   } else if (symbol.has<UnknownDetails>()) {
     symbol.set_details(ObjectEntityDetails{});
   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
     symbol.set_details(ObjectEntityDetails{std::move(*details)});
   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
     return useDetails->symbol().has<ObjectEntityDetails>();
+  } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
+    return hostDetails->symbol().has<ObjectEntityDetails>();
   } else {
     return false;
   }
   return true;
 }
 // Convert symbol to be a ProcEntity or return false if it can't be.
 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
   if (symbol.has<ProcEntityDetails>()) {
     // nothing to do
   } else if (symbol.has<UnknownDetails>()) {
     symbol.set_details(ProcEntityDetails{});
   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
     symbol.set_details(ProcEntityDetails{std::move(*details)});
     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
       CHECK(!symbol.test(Symbol::Flag::Subroutine));
       symbol.set(Symbol::Flag::Function);
     }
+  } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
+    return useDetails->symbol().has<ProcEntityDetails>();
+  } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
+    return hostDetails->symbol().has<ProcEntityDetails>();
   } else {
     return false;
   }
   return true;
 }
 
 const DeclTypeSpec &ScopeHandler::MakeNumericType(
     TypeCategory category, const std::optional<parser::KindSelector> &kind) {