upgrade of DROP CONSTRAINT

[TarantoolBot]

Related dev. issue(s): tarantool/tarantool#9112

Product: Tarantool
Since: 3.0
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_statements_and_clauses/#alter-table
SME: @ ImeevMA

Details

Now, instead of just ALTER TABLE table DROP CONSTRAINT constraint; we
have 8 operator variants:

1. Statement to drop PRIMARY KEY, UNIQUE, tuple FOREIGN NEY or tuple
   CHECK constraints:

ALTER TABLE tab_name DROP CONSTRAINT constr_name;

This statement cannot drop a constraint if constr_name matches
more than one constraint.

2. Statement to drop field FOREIGN NEY or field CHECK constraints:

ALTER TABLE tab_name DROP CONSTRAINT field_name.constr_name;

This statement cannot drop a constraint if constr_name matches
more than one constraint for the field_name field.

3. Statement to drop PRIMARY KEY constraint:

ALTER TABLE tab_name DROP CONSTRAINT constr_name PRIMARY KEY;

4. Statement to drop UNIQUE constraint:

ALTER TABLE tab_name DROP CONSTRAINT constr_name UNIQUE;

5. Statement to drop tuple FOREIGN KEY constraint:

ALTER TABLE tab_name DROP CONSTRAINT constr_name FOREIGN KEY;

6. Statement to drop tuple CHECK constraint:

ALTER TABLE tab_name DROP CONSTRAINT constr_name CHECK;

7. Statement to drop field FOREIGN KEY constraint:

ALTER TABLE tab_name DROP CONSTRAINT field_name.constr_name FOREIGN KEY;

8. Statement to drop field CHECK constraint:

ALTER TABLE tab_name DROP CONSTRAINT field_name.constr_name CHECK;

Requested by @ ImeevMA in tarantool/tarantool@263777d.