Integrate sql-pg-restrict and sql-pg-helper

[Sharaal]

As a proposal integrate both additional packages into the core sql-pg package.

This results in a few advantages:

• All methods are provided with the sql tag, so it will be sql.query, sql.insert and so on available
• All of these methods are optional available after assign the pg client to sql.client
• sql.query will be automatically restricted to queries created with the sql tag
• Avoid complex usage if want to use them together

The disadvantage is of course the higher complexity of the core sql-pg package.