Add support for optional COLUMN in ALTER TABLE CHANGE query

[costasovo]

This PR addresses an issue where the ALTER TABLE CHANGE with skipped COLUMNS keyword was ignored.

-- Processed correctly
ALTER TABLE _tmp_table CHANGE COLUMN name firstname varchar(50) NOT NULL default 'mark';

-- Was ignored
ALTER TABLE _tmp_table CHANGE name firstname varchar(50) NOT NULL default 'mark';

This PR fixes the issue by adding support for optional COLUMN in the ALTER TABLE CHANGE query

[adamziel]

Looks great to me, thank you so much for your contribution @costasovo!