Refactor: Replace Form with Campaign in step 1 of Setup Guide

[pauloiankoski]

Resolves GIVE-2266

Description

This pull request includes changes to the src/Onboarding/Setup/templates/index.html.php file to update the terminology and functionality related to donation forms and campaigns. The most important changes include replacing references to donation forms with campaigns and updating URLs accordingly.

Terminology and functionality updates:

• Removed the import statement for DonationForm as it is no longer needed.
• Changed the variable from $form to $campaign and updated the method to retrieve the campaign by form ID.
• Updated the URL for customizing the campaign, replacing the form-related URL with the campaign-related URL.
• Modified the title to refer to creating a campaign instead of a donation form.
• Updated the button text from "Customize form" to "Customize campaign" and adjusted the URL accordingly.

Affects

Step 1 of Setup Guide

Visuals

Testing Instructions

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