json_form_widget throws deprecation messages in PHP 8.2

[paul-m]

Now that PHP 8.2 is our default testing environment, 10_workflow_transitions.spec.js fails because json_form_widget adds dynamic properties to classes. It emits a message like this:

Deprecated function: Creation of dynamic property Drupal\Core\Form\FormState::$has_json_form_widget is deprecated in json_form_widget_field_widget_complete_form_alter() (line 79 of /var/www/html/dkan/modules/json_form_widget/json_form_widget.module).

This PR:

• Modifies json_form_widget_field_widget_complete_form_alter() and json_form_widget_form_alter() to use FormStateInterface::get() and set() to store information rather than the now-deprecated technique of setting a new dynamic property on the form state object.
• Converts 07_admin_dataset_json_form.spec.js and 11_admin_dataset_file_upload.spec.js to be BrowserTestBase tests. This way the deprecation shows up in PHP scope. We can't count on Cypress to fail for a deprecation, but they'll stand out in PHPUnit-land.
• Improves other tests in json_form_widget with group annotation.
• Limits PHPUnit test coverage so that we're not showing coverage for tests.

To manually test:

• Create a local development environment using PHP 8.2 using this branch.
• git checkout 2.x modules/json_form_widget/json_form_widget.module
• ddev dkan-phpunit --filter AdminDatasetJsonFormTest
• This test will error due to the deprecation.
• git restore --staged modules/json_form_widget/json_form_widget.module
• git restore modules/json_form_widget/json_form_widget.module
• ddev dkan-phpunit --filter AdminDatasetJsonFormTest
• No deprecation error.