Fixes #5587: `json_encode` is now used with `JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE` where it makes sense, also it is now default for `Json::encode()`

This fix ensures the format configured in the formatter class is used in the message instead
of the default ICU format.

fixes #4960

fixes #4602, close #4624

fixes #4045

I think it's better to enclose `$key` as function parameter.

allow using it from the gridview directly

Adjustments code according to the standards.
Adding missing PHPDoc comment.

issue #2852

use toRoute() instead of createUrl() in ActionColumn