Add pg_tables and pg_views to catalog

[skabbes]

Supersedes: #1748

Fixes: #1747

Problem - I was unable to write a query against pg_timezone_names.

Actual failing query

select
  name,
  abbrev,
  utc_offset,
  to_char((current_timestamp at time zone name), 'HH:MI am') as current_time
from pg_catalog.pg_timezone_names
order by utc_offset;

This because sqlc did not know about these built-in tables / views.