WL#13070: Deprecate && (resp. ||, !) as synonym for AND (OR, NOT) in SQL statements

In MySQL, the following two statements are synonymous:

  SELECT * FROM t WHERE a > 0 AND b > 0;
  SELECT * FROM t WHERE a > 0 && b > 0;

Likewise for the OR operator:

  SELECT * FROM t WHERE a > 0 OR b > 0;
  SELECT * FROM t WHERE a > 0 || b > 0;

And for the NOT operator:

  SELECT * FROM t WHERE NOT a > 0;
  SELECT * FROM t WHERE ! a > 0;

The operators &&, || and ! are all invalid according to the SQL standard and are
completely redundant. In addition, we do not think they are used much in actual
SQL statements.

In addition, the || symbol conflicts with the standard SQL concatenation
operator. When this has been removed as synonym for OR, we can allow || as
concatenation operator without requiring a special SQL mode (PIPES_AS_CONCAT,
currently).

F1 A warning should be sent when the query uses one of these operators:
- ! (warning should suggest NOT)
- && (warning should suggest AND)
- || if sql_mode doesn't have the PIPES_AS_CONCAT flag (in which case || does
OR, not CONCAT) (warning should suggest OR).

F2 No other behaviour change