Format constant declarations relative to their enclosing scope

[pvcresin]

This PR fixes scenario/known-issues/const-scope.rb‎.

# before
class C
  C::D: Integer
end

# after
class C
  D: Integer
end

Details

• dump_declarations now prints class/module-local constants as relative names
  (e.g. D: Integer instead of C::D: Integer inside class C).
• Moved const-scope from scenario/known-issues to scenario/const since it now passes.
• Updated affected scenario expectations to match the new output format.

This change is about declaration rendering only; core type inference behavior is unchanged.

[mame]

Looks great!