Feature: Form template registration

[jonwaldstein]

Description

We recently introduced the initial template api as it relates to customizing the front-end. This PR accompanies that by adding a template registration system so new Templates can get registered and pull in their front-end assets.

One of the goals for Templates, is keeping it as simple as possible. If someone wants to create a template that just pulls in some CSS we want them to get up and running easily. Here is a birds eye view of a template simplicity using the (work-in-progress) classic template as an example:

class ClassicFormTemplate extends FormTemplate {

    public static function id(): string
    {
        return 'classic';
    }

    public static function name(): string
    {
        return __('Classic Template', 'give');
    }

    public function css(): string
    {
        return GIVE_NEXT_GEN_URL . 'src/NextGen/DonationForm/FormTemplates/ClassicFormTemplate/template.css';
    }

    public function js(): string
    {
        return GIVE_NEXT_GEN_URL . 'src/NextGen/DonationForm/FormTemplates/ClassicFormTemplate/template.js';
    }
}

add_action('givewp_register_form_template', function (FormTemplateRegistrar $formTemplateRegistrar) {
    $formTemplateRegistrar->registerTemplate(ClassicFormTemplate::class);
});

Affects

The new "classic form" was created as the new default for next gen forms. Viewing the form should reflect some basic CSS to show the template is active. Note - this PR is not intended to have a complete version of the Classic Template - just using it for a tangible example until we're ready to build it out.

Also added phpunit here out of necessity.

Visuals

Testing Instructions

View a NextGen form and see some basic css applied. This is the start of what will soon be the Classic Template.

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[github-actions]

A build of this branch is available at https://impress-org.github.io/givewp-next-gen/feature/template-registration

[jonwaldstein]

@kjohnson this is ready for review.

[kjohnson]

@jonwaldstein added my review - mostly questions and additional commentary. Otherwise, not opposed to this getting merged soon, so I submitted the review as a "Comment" as opposed to "Request Changes".

[github-actions]

A build of this branch is available at https://impress-org.github.io/givewp-next-gen/develop