The existing syntax for renaming a column uses "ALTER TABLE ...  CHANGE"
command. This requires full column specification to rename the column.
This patch adds new syntax "ALTER TABLE ...  RENAME COLUMN", which do not
expect users to provide full column specification.  It means that the new
syntax would pick in-place or copy algorithm in the same way as that of
existing "ALTER TABLE ... CHANGE" command. The existing syntax
"ALTER TABLE ... CHANGE" will continue to work.

Syntax changes
==============

ALTER TABLE tbl_name
    [alter_specification [, alter_specification] ...]
    [partition_options]

Following is a new <alter_specification> added:

 | RENAME COLUMN <oldname> TO <newname>

Where <oldname> and <newname> are identifiers for old name and new
name of the column.

Related to: WL#10761