Feature: Modify alter table column parser II

[wubx]

Summary

Now

ALTER TABLE [ IF EXISTS ] [ <database_name>. ]<table_name> 
MODIFY [ COLUMN ] <column_name> <new_data_type> [ DEFAULT <constant_value> ][, COLUMN <column_name> <new_data_type> [ DEFAULT <constant_value> ], ... ]

alter table T modify c1 varchar, column c2 varchar;

improve

ALTER TABLE [ IF EXISTS ] [ <database_name>. ]<table_name> 
MODIFY [ COLUMN ] <column_name> <new_data_type> [ DEFAULT <constant_value> ][, [ COLUMN ] <column_name> <new_data_type> [ DEFAULT <constant_value> ], ... ]

alter table T modify c1 varchar, c2 varchar;

[wubx]

References: #14533

[TracyZYJ]

Please assign me :)

[BohuTANG]

Doc has updated: databendlabs/databend-docs@ef7d4c3, cc @soyeric128