Fixes #4938: When `yii\db\ActiveQuery` is used to build sub-queries, its WHERE clause is not correctly generated

- do not allow boolean values for integer columns
- use native boolean type with boolean values
- removed workaround that turned out to be wrong when schema and values
  are used correctly. Workaround resulted from wrong usage of boolean
  values before.

fixes #4672

issue #4687

also fixed an issue with default value loading of bool columns.

fixes #3489, fixes #4085, fixes #3920
related to #4672

fixes #4654

close #4655

Added support for arbitrary operators to Query::filterWhere, added support for arbitrary operators to Sphinx extension

Adjusted Connection::transaction to provide Connection instance by default instead of transaction instance

Fixes #3568: When the primary query sets `asArray`, it is not respected by the `via` relational query

fixes #422

fixed some issues with schema detection

issue #3520