Fix: missing Landing Page for the campaign created during the onboarding wizard

[glaubersilva]

Resolves GIVE-2282

Description

This PR moves the logic to create a new campaign landing page from the CampaignRequestController.php file to the givewp_campaign_created hook which is proper because this way we can have the landing page created and attached to the campaign automatically when using the Campaign::create() method. So these changes fix the bug that was creating the campaign on the onboarding wizard without a campaign landing page attached to it.

Affects

The campaign creation workflow and the campaign creation on the onboarding wizard.

Visuals

This PR fixes this bug:

https://www.loom.com/share/d6800929b2fd4f7f9082d4a86a9ef79f?sid=d37c73d1-8dc6-437b-9cfa-274dd55a8994

Testing Instructions

1. You can create a new test site or enable the Give > Settings > Advanced > Setup Page option and delete all your campaigns/forms directly on DB.
2. Access the Setup page and create the onboarding campaign;
3. Go to the campaign details page created previously and make sure the "View Campaign" link is available on the 3 dots menu;
4. Click on the "Edit campaign page" button and make sure you are not redirected to the wp-admin/edit.php page.

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

[pauloiankoski]

I liked it! We are now creating the campaign page in the same way we create the donation form, ensuring that all side effects of campaign creation follow the same pattern.