Allow 'use' in class scope

[lydia-duncan]

The spec and compiler currently don't allow 'use' statements at the same scope as field and method declarations. It seems useful to do so, for 'use' of both enums and classes.

Steps to Reproduce

Source Code:

enum classTag { field1, field2};

class Foo {
  use classTag;

  var tag: classTag = field1;
}

Compile command:
chpl foo.chpl

Associated Future Test(s):
test/types/enum/lydia/declaredInClass2.chpl
test/types/enum/lydia/useAtClassScope.chpl
#6870

Configuration Information

• Output of chpl --version: 1.16.0 (prerelease)