ignore type symbols in lookup when enum type is expected

[metagn]

fixes #23689

When an identifier expression expects an enum type, when looking up the identifier as a symbol, type symbols are ignored, i.e.

type
  Foo = enum A, B
  C = object

let x: Foo = C

will give an "undeclared identifier" error. This is to make #23689 work in the least obtrusive way, it might cause other problems. It could also be generalized to all concrete types (expected.kind in ConcreteTypes instead of == tyEnum).

[Araq]

Regressions aside, this rule makes no sense to me. C is not an "undeclared" identifier, it's just that a type cannot be used as a value here.