Fix nested conditions, polymorphic associations handling

[bopm]

Fix nested conditions, polymorphic associations handling

This PR addresses several issues with Ransack's handling of polymorphic associations and negative predicates:

Key Improvements

1. Polymorphic Association Support: Added proper handling for polymorphic associations in correlated subqueries by correctly managing both foreign key and type columns.

2. Negative Predicate Handling: Fixed the behavior of negative predicates (not_null, not_cont, etc.) when used with associations:

   • not_null: true/false now generates the correct IN/NOT IN queries
   • not_cont now properly generates NOT IN queries with LIKE conditions

3. Complex AND Conditions: Improved extraction of correlated keys from complex AND conditions with multiple children.

4. String Wildcard Handling: Added proper quoting for string values containing wildcards (%) in LIKE predicates.

5. Nested Condition Detection: Added helper method to correctly identify nested vs. non-nested conditions.

Tests Added

• Tests for wildcard string handling in LIKE/NOT LIKE predicates
• Tests for negative conditions on associations
• Tests for nested condition identification
• Comprehensive tests for polymorphic associations with not_in predicate
• Tests for complex AND conditions with multiple children

Other Changes

• Removed pending status from a previously failing test that now passes
• Added .idea to .gitignore

This PR fixes issues with complex queries involving polymorphic associations and negative predicates, which previously generated incorrect SQL.

This PR incorporates changes from #1537 and #1279.