Use "skip verify permission to determine if form should redirect

Problem/Motivation

Currently, the VerifyEmailForm will only display the verification form if the user is not logged in. Logged in users will be directed to the destination page immediately. This makes the module inflexible as sites may want to use it for logged in users.

Steps to reproduce

Create a verification form. Go to form URL as any logged in user. Verify redirect to destination occurs.

Proposed resolution

"skip verify $id" permission has been created, so change check on form to only redirect for users with permission.

Remaining tasks

1. This issue is dependent on #3556368: Create custom permissions per verification form, so check that has been merged.
2. In the BuildForm function, after saving the entity to the form state, add $id = $entity->id()
3. Edit VerifyEmailForm and change $this->currentUser()->isAuthenticated() to $this->currentUser->hasPermission('skip verify $id')
4. In VerifyEmailRoutingTest:
   • Add a new skipUser class property.
   • In setUp, after saving the VerifyEmail entity, use drupalCreateUser to create a user with "skip verify verify_email_test" permission, and assign to the $this->skipUser property.
   • Replicate the testVerifyEmailRouteAuthenticatedUser function and give the copy a new name, and change to login as $this->skipUser.
   • Change the original testVerifyEmailRouteAuthenticatedUser to check the path remains "/verify-email-form", since the admin user doesn't have the "Skip" permission.
   • Update comment on both functions to explain the permission difference.

User interface changes

None.

API changes

None.

Data model changes

None.