Support sqlite; set sqlite_type to native JSON field

Problem/Motivation

NativeJSONItem field sets 'type' => 'json' in its schema definition. In case you have json_native field and running tests with SQLite database this results in an exception:

Undefined array key "json:normal"

/web/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php:142
/web/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php:97
/web/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php:61
/web/core/lib/Drupal/Core/Database/Schema.php:616
/web/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php:421

The reason is that json datatype does not exist in SQLite https://www.sqlite.org/datatype3.html.

Steps to reproduce

* Add json_native field to an entity
* Run tests with SQLite database
* Undefined array key "json:normal" message occurs

Proposed resolution

Add 'sqlite_type' => 'text' in NativeJSONItem class.

Remaining tasks

User interface changes

API changes

Data model changes