Memory-resource porting checklist for current resource free `CUDF_TEST_EXPECT_[COLUMNS/TABLES]_EQUAL` use

[nirandaperera]

Track migration to explicit cudf::memory_resources, separating returned allocations from temporary allocations and preventing fallback to the current device resource.

Completed

• Memory-resource abstraction and test harness [cudf] Adding memory_resources support for column wrappers #23581
  • cudf::memory_resources
  • BaseFixtureWithHarness
  • cpp/include/cudf/utilities/memory_resource.hpp
  • cpp/include/cudf_test/base_fixture.hpp
• Equality preprocessing and row hashing [cudf] Thread memory resources through equality/hash row preprocessing #23665
  • Equality preprocessed_table, comparators, and hash preprocessing
  • Lexicographic preprocessing remains separate and incomplete.
• Primary column-wrapper allocation paths
  • Fixed-width, string, dictionary, and initializer resource forwarding
  • cpp/include/cudf_test/column_wrapper.hpp
  • Recursive list concatenation remains incomplete.
• Gather [cudf] Route dictionary encode and gather temps through memory_resources #23642
  • Public/detail gather and type-specific dispatch
  • cpp/include/cudf/detail/gather.*
  • cpp/src/copying/gather.cu
• Segmented gather
  • List segmented-gather entry points and recursion
  • cpp/include/cudf/lists/gather.hpp
  • cpp/src/lists/copying/segmented_gather.cu
• Dictionary encode/decode
  • Public/detail APIs, row hashing, gather, and output masks
  • cpp/include/cudf/dictionary/encode.hpp
  • cpp/src/dictionary/{encode,decode}.cu

Remaining

• Generic device algorithms
  • Port transform_reduce, count_if, copy_if, and related helpers.
  • cpp/include/cudf/detail/algorithms/
• Validity-mask construction
  • Port detail::valid_if to use output and temporary resources.
  • cpp/include/cudf/detail/valid_if.cuh
• Null counting and sliced views
  • Port null_count, segmented_null_count, batch_count_set_bits, slice, and split.
  • Port list/struct get_sliced_child.
  • cpp/src/bitmask/null_mask.cu
  • cpp/src/copying/{slice,split}.*
  • cpp/src/lists/lists_column_view.cu
  • cpp/src/structs/structs_column_view.cpp
• Non-empty-null detection
  • Port has_nonempty_nulls and has_nonempty_null_rows.
  • Update test assertion callers.
  • cpp/src/copying/purge_nonempty_nulls.cu
  • cpp/tests/utilities/column_utilities.cu
• Concatenate
  • Port public/detail column, table, and mask APIs.
  • Port fixed-width, string, list, struct, and dictionary implementations.
  • cpp/src/copying/concatenate.cu
  • cpp/src/{strings,lists,structs}/copying/concatenate.cu
  • cpp/src/dictionary/detail/concatenate.cu
• Recursive list column wrappers
  • Pass the full resource pair into concatenate.
  • Add harness coverage for nullable nested initializers.
  • cpp/include/cudf_test/column_wrapper.hpp
• Lexicographic row preprocessing
  • Port preprocessed_table, self_comparator, and two_table_comparator.
  • cpp/include/cudf/detail/row_operator/lexicographic.cuh
  • cpp/src/row_operator/row_operators.cu
• Dremel list preprocessing
  • Port get_dremel_data, get_comparator_data, device vectors, and algorithm scratch.
  • cpp/include/cudf/lists/detail/dremel.hpp
  • cpp/src/lists/dremel.cu
• Ranking and sorted order
  • Port rank, sorted_order, and stable_sorted_order.
  • cpp/include/cudf/{detail/,}sorting.hpp
  • cpp/src/sort/
• List offset normalization
  • Port lists::detail::get_normalized_offsets.
  • cpp/src/lists/utilities.cu
• Regression coverage
  • Add resource-routing tests for concatenate dispatch.
  • Add recursive nullable-list wrapper tests.
  • Fix debug/failure assertion paths that pass a single MR and recapture current MR.

Acceptance tests

./gtests/COPYING_TEST \
  --gtest_filter='Gather*:SegmentedGather*:StructGather*:TypedStructGather*'
./gtests/DICTIONARY_TEST \
  --gtest_filter='DictionaryEncode*:DictionaryDecode*'
./gtests/ROW_OPERATOR_TEST \
  --gtest_filter='TypedTableView*:NaNTableView*:RowOperator*'
./gtests/UTILITIES_TEST \
  --gtest_filter='*ColumnWrapperTest*'