Element authorization improvements

[brandonkelly]

This PR adds element authorization-check methods and events to the Elements service, with the same names as their craft\base\Element counterparts:

• craft\services\Elements::canView() + EVENT_AUTHORIZE_VIEW
• craft\services\Elements::canSave() + EVENT_AUTHORIZE_SAVE
• craft\services\Elements::canDuplicate() + EVENT_AUTHORIZE_DUPLICATE
• craft\services\Elements::canDelete() + EVENT_AUTHORIZE_DELETE
• craft\services\Elements::canDeleteForSite() + EVENT_AUTHORIZE_DELETE_FOR_SITE
• craft\services\Elements::canCreateDrafts() + EVENT_AUTHORIZE_CREATE_DRAFTS

There are two notable differences between these and the authorization methods/events on craft\base\Element:

• The methods’ $user argument is optional. If null, it will default to the currently logged-in user, or return false if there isn’t one.
• AuthorizationCheckEvent::$authorized is set to null by default, and the methods will only defer to the element’s corresponding canX() method if an event handler hasn’t explicitly set it to true or false. Which means event handlers have the ability to prevent users from being authorized for certain actions, as opposed to only being able to authorize them (see [4.x]: Issue with `Element::EVENT_AUTHORIZE_DELETE` ? #11759).

All internal authorization checks have been updated to call the new Elements service methods. And the old events on craft\base\Element are now deprecated, since they’re redundant and less useful.

Finally, there’s new global Twig functions that wrap the new Elements service methods, making it a lot easier to check if the current user is authorized to do something with an element: (#11797)

{% if not canView(entry) %}
    {% redirect siteUrl %}
{% endif %}

[linear]

DEV-984 Element authorization improvements