BUG #19023: Table DDL default column expression depending on temp objects

The following bug has been logged on the website:

Bug reference: 19023
Logged by: Kirill Reshke
Email address: reshkekirill(at)gmail(dot)com
PostgreSQL version: 18beta3
Operating system: any
Description:

I have found two cases when user can define a relation, which has temp
objects in its DEFAULT expression.
First example is:
```
reshke=# create temp sequence s1;
CREATE SEQUENCE
reshke=# create table tt(i int default nextval('s1'));
CREATE TABLE
```
I think it is a bug that PostgreSQL allows this DDL to successfully
complete. There is a validation for this type of DDL already, example:
```
reshke=# create table ttx(i int default nextval('s3'));
ERROR: relation "s3" does not exist
LINE 1: create table ttx(i int default nextval('s3'));
^

```

Since PostgreSQL already checks for its nextval() input, we can teach server
to also validate relation relpersistence, arent we?

Second example is with tables:
```
reshke=# create temp table x();
CREATE TABLE
reshke=# create table y (i int default nextval('x'));
CREATE TABLE
reshke=# insert into y default values ;
ERROR: cannot open relation "x"
DETAIL: This operation is not supported for tables.

```

WDYT? Is this indeed a bug?