Using ref in a filter gives an error in ash 3

[ahey]

Describe the bug
Filtering on a ref was working up until Ash 3.0. Now, it gives an error.

To Reproduce
A PR with a failing test has been added to demonstrate the error. Running the test give the following error:

1. test filter with ref (AshPostgres.FilterTest)
   test/filter_test.exs:1076
   ** (FunctionClauseError) no function clause matching in Ash.Filter.check_filterable/2

   The following arguments were given to Ash.Filter.check_filterable/2:

     # 1
     AshPostgres.Test.Organization
   
     # 2
     :id
   

   Attempted function clauses (showing 2 out of 2):

     defp check_filterable(_resource, [])
     defp check_filterable(resource, [relationship | rest])
   

   code: |> Ash.Query.filter(^ref(:id, [:posts, :comments]) == ^comment.id)
   stacktrace:
   (ash 3.0.1) lib/ash/filter/filter.ex:2944: Ash.Filter.check_filterable/2
   (ash 3.0.1) lib/ash/filter/filter.ex:2933: anonymous fn/2 in Ash.Filter.validate_filterable_relationship_paths/2
   (elixir 1.16.2) lib/enum.ex:4316: Enum.find_value_list/3
   (ash 3.0.1) lib/ash/filter/filter.ex:2923: Ash.Filter.validate_refs/3
   (ash 3.0.1) lib/ash/filter/filter.ex:3015: Ash.Filter.resolve_call/2
   (ash 3.0.1) lib/ash/filter/filter.ex:2489: Ash.Filter.add_expression_part/3
   (ash 3.0.1) lib/ash/filter/filter.ex:2427: anonymous fn/3 in Ash.Filter.parse_expression/2
   (elixir 1.16.2) lib/enum.ex:4839: Enumerable.List.reduce/3
   (elixir 1.16.2) lib/enum.ex:2582: Enum.reduce_while/3
   (ash 3.0.1) lib/ash/filter/filter.ex:334: Ash.Filter.parse/3
   (ash 3.0.1) lib/ash/query/query.ex:2574: Ash.Query.do_filter/3
   test/filter_test.exs:1095: (test)

[zachdaniel]

So, not sure if this changed in 2.0 -> 3.0, if so, sorry about that :)

But its ^ref([:path, :to], :field)

[zachdaniel]

I'm adding some pattern matching to ref/2 and ref/1 to help make it clearer.

[ahey]

Thanks Zach!