Sliding window execution fails for covar_pop, covar_samp, and corr

[pchintar]

Describe the bug

Bounded sliding window queries using covar_pop, covar_samp, and corr fail with a "retract_batch is not implemented" error, even though these aggregates otherwise work correctly.

To Reproduce

CREATE TABLE sliding_corr_test AS
VALUES
  (1, 10.0),
  (2, 20.0),
  (3, 30.0);

SELECT
  column1,
  covar_pop(column2, column2) OVER (
    ORDER BY column1
    ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING
  ) AS cp,
  covar_samp(column2, column2) OVER (
    ORDER BY column1
    ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING
  ) AS cs,
  corr(column2, column2) OVER (
    ORDER BY column1
    ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING
  ) AS c
FROM sliding_corr_test;

Expected behavior

The query should execute successfully and return covariance/correlation values for the specified window frame, similar to how other aggregates that support bounded sliding windows behave.

Actual Result

This feature is not implemented: Aggregate can not be used as a sliding accumulator because `retract_batch` is not implemented: covar_pop(sliding_corr_test.column2, sliding_corr_test.column2) ORDER BY [sliding_corr_test.column1 ASC NULLS LAST] ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING

The same error occurs for other bounded sliding frames, for example:

ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING