sql: \d command to include RLS policies

[spilchen]

Row-level security (RLS) policies should be displayed when the table is included in the output of \d.

We should aim to closely follow PostgreSQL's output format, as shown in this example:

postgres=# \d cities;
Table "public.cities"
Column |     Type     | Collation | Nullable | Default
----------------------------------------------------
state  | text         |           |          |
pop    | numeric(9,3) |           |          |
name   | text         |           |          |
Policies:
POLICY "easy"
WITH CHECK (true)

Jira issue: CRDB-46367