Refactor `CRUD::delete` method to support advanced DELETE queries (#25)

The current implementation relies on `wpdb::delete`, which supports only simple `where x = y` conditions. It's not only incomplete but also dangerous because `Where::$comparisonOperator` and `Where::$logicalOperator` are just ignored, so the result is unpredictable. The following change provides a way to use existing QueryBuilder functionality to generate DELETE SQL. The documentation describes some restrictions.

Merge pull request #21 from stellarwp/bugfix/php-types

Bugfix: PHP doc types

Merge pull request #16 from binarygary/feature/upsert

Add a basic upsert method

Merge pull request #15 from stellarwp/fix/php-8.1-deprecation

Don't `trim( null )`

Merge pull request #14 from stellarwp/bugfix/exception-array-shape

Fix array shape for errors in DatabaseQueryException

Merge pull request #13 from stellarwp/fix-where-exists-return-type

Merge pull request #12 from stellarwp/fix-db-table-phpdoc

Fix DB::from() PHPDoc

Updating changelog for 1.0.3

Updating release date of v1.0.2

Merge pull request #1 from stellarwp/feature/config

Add a config class to provide some customizability