Extend get and get! Methods to Support Raw SQL Subquery Filtering

[treagod]

Description

Following up on Issue #44, where the ability to filter records using raw SQL subquery predicates was added to the filter method, it would be useful to implement similar functionality for the get and get! methods.

Currently, a workaround like Post.filter("access_token = ?", access_token).first is required to achieve this, but it would be more convenient and intuitive to allow raw subquery predicates directly within the get and get! methods.

Tasks

Modify the get and get! methods to accept raw SQL subquery predicates, similar to how the filter method works.
Allow these predicates to be passed along with parameters in either positional or named form.