Split equivalence code into smaller modules. (apache#8649)

* refactor

* refactor

* fix imports

* fix ordering

* private func as pub

* private as pub

* fix import

* fix mod func

* fix add_equal_conditions_test

* fix project_equivalence_properties_test

* fix test_ordering_satisfy

* fix test_ordering_satisfy_with_equivalence2

* fix other ordering tests

* fix join_equivalence_properties

* fix test_expr_consists_of_constants

* fix test_bridge_groups

* fix test_remove_redundant_entries_eq_group

* fix proj tests

* test_remove_redundant_entries_oeq_class

* test_schema_normalize_expr_with_equivalence

* test_normalize_ordering_equivalence_classes

* test_get_indices_of_matching_sort_exprs_with_order_eq

* test_contains_any

* test_update_ordering

* test_find_longest_permutation_random

* test_find_longest_permutation

* test_get_meet_ordering

* test_get_finer

* test_normalize_sort_reqs

* test_schema_normalize_sort_requirement_with_equivalence

* expose func and struct

* remove unused export