allow conditions like ts < expr(now()) in temporal filter

[stdrc]

No description provided.

[stdrc]

Actually this is already done after #11454 and #14098.

[st1page]

dev=> explain create materialized view mv as     select * from t1 where ts + interval '1 hour' < date_trunc('DAY',now());
ERROR:  Failed to run the query

Caused by:
  Conditions containing now must be of the form `input_expr cmp now() [+- const_expr]` or `now() [+- const_expr] cmp input_expr`, where `input_expr` references a column and contains no `now()`.