Fixes #6361: Added `validateAttribute()` to `yii.activeForm.js` to support manually triggering data validation of an input

Allow attributes to have their validation triggered by a custom event.
`validateAttribute` is called with `forceValidate` set to true.

Fixes #6661: Hyperlinks that are enclosed within an exist form will use the same form for submission if they specify both of the `href` and `data-method` attributes

Fixes #5663 and #5671: Added support for using `data-params` to specify additional form data to be submitted via the `data-method` approach

Fixes #6467: `ActiveForm` will scroll to the nearest visible element when the first error input is hidden

Fixes #6345

Fixes #5863: Selecting all individual `yii\grid\CheckboxColumn` checkboxes in grid view wasn't resulting in "all" checkbox selected

Fixes #5768: When setting `data-confirm` attribute to a submit button, clicking on the button would not trigger form submission

Removed `form` as a parameter to the events since it can be retrieved using `$grid.find('form.gridview-filter-form')`.

Events `beforeFilter.yiiGridView` and `afterFilter.yiiGridView` javascript events created for advanced use cases.

Trigger a new `filter.yiiGridView` event for yii grid view after grid filters are applied. This will enable developer to code a lot of use cases based on the grid filtering event. The filter `$form` can be accessed as a parameter to the event.

Fixes #3581: Added `yii\validators\CompareValidator::type` to support type conversion before comparing values

Fixes #3511: Dropped `yii.allowAction()` and modified `yii.confirm()` in `yii.js` to support callbacks