feat: support releasing batches in RecordBatchMemoryCounter

[txwyy123]

Which issue does this PR close?

Closes #26140.

Rationale for this change

RecordBatchMemoryCounter can only add buffers — there is no way to stop counting a batch. This means operators that retain batches incrementally and drop them later (sort, window, sort-merge join, TopK) cannot use it and must keep their own estimates instead, leading to the over-counting and not-counted problems described in #26140.

What changes are included in this PR?

Add uncount_batch, uncount_array, and uncount_batch_with_array_overhead methods to RecordBatchMemoryCounter. The internal BufferIdSet (insert-only set) is replaced with BufferIdMap (reference-counted map):

• Counting a batch increments the count of each of its buffers; a buffer's capacity is added to memory_usage only when its count goes from 0 to 1 (identical to today's behavior).
• Uncounting a batch decrements the counts and returns the bytes released: the capacities of buffers whose count reaches 0.

The per-type buffer walk (null buffers, offsets, view buffers including variadic data buffers, dictionaries, nested children, the ArrayData fallback) is shared between counting and uncounting via a unified visit_array_buffers method with a BufferOp direction parameter — no duplication.

The inline fast path for ≤16 distinct buffers is preserved (allocation-free for typical batches).

Existing behavior preserved

All existing count_* methods return exactly what they returned before. No caller changes needed. All 22 existing tests pass unchanged.

How was this tested?

Unit tests (8 new)

Test	Coverage
test_uncount_batch_round_trip	count then uncount returns to 0
test_uncount_two_slices_example_from_issue	The exact table from #26140
test_uncount_array_round_trip	Single array count/uncount
test_uncount_batch_with_array_overhead_round_trip	Full round-trip with array overhead
test_uncount_view_arrays_sharing_data_buffers	StringView with data buffers
test_uncount_dictionaries_sharing_values	Two dictionaries sharing values array
test_uncount_nested_struct	Nested struct type
test_uncount_with_overflow_promotion	>16 distinct buffers with removals
test_uncount_never_counted_is_noop	Uncount of never-counted buffer
test_randomized_count_uncount_sequence	Randomized sequence checked against reference model

Benchmark

New count_uncount benchmark group added. No regression on existing counting benchmarks:

record_batch_memory_size/column_count/1    time: [21.9 ns]
record_batch_memory_size/column_count/4    time: [63.3 ns]
record_batch_memory_size/column_count/16   time: [285.6 ns]
record_batch_memory_size/column_count/64   time: [2.12 µs]
record_batch_memory_size/shared_slices/4   time: [1.84 µs]
record_batch_memory_size/shared_slices/16  time: [8.72 µs]
record_batch_memory_size/shared_slices/64  time: [30.1 µs]
record_batch_memory_size/count_uncount/4   time: [3.74 µs]  (new)
record_batch_memory_size/count_uncount/16  time: [~15 µs]   (new)
record_batch_memory_size/count_uncount/64  time: [~52 µs]   (new)

[txwyy123]

Closing for now — will reopen after further review.

[jayzhan211]

You can turn it to draft instead of closing it