Server: Ability to use `current_setting('hasura.user')` in Views

right now for mutation transactions have `hasura.user` available to them but It would be nice to have it available for views as well so we can do something like
```sql
CREATE VIEW user_articles AS
SELECT id, title, content from articles
where author_id = current_setting('hasura.user') :: json ->> 'x-hasura-user-id'
```

No files or tests are named. Start by comparing how hasura.user is made available during mutation transactions with how PostgreSQL views are executed; done means the setting is available to views so the demonstrated current_setting query can filter rows as intended.

Written by the indexing model from the issue text.