feat: implement newsletter subscription feature with new forms and database structure

- Added new newsletter subscription functionality to the participation page.
- Created a new `NewsletterForm` component to handle user subscriptions.
- Introduced `NewsletterSubscriptions` collection to manage subscriptions in the database.
- Developed migration script to set up necessary database tables and fields for the newsletter feature.
- Refactored participation content to remove deprecated newsletter phase data and integrate new structure.
- Updated the `Participation` page to utilize the new newsletter form and handle different application phases.

src/scripts/preload-globals-cms.ts

@@ -6,6 +6,7 @@ import { mediaByFilename } from './mediaByFilename'
 
 import { defaultApplicationPhaseData } from '@/spa/applicationPhase'
 import { defaultFooterData, defaultHeaderData } from '@/spa/cmsNavigation'
+import { defaultNewsletterFormData } from '@/spa/newsletterForm'
 import { defaultSiteSettings } from '@/spa/siteSettings'
 
 async function main() {
@@ -59,6 +60,11 @@ async function main() {
       context: { disableRevalidate: true },
       data: defaultApplicationPhaseData as never,
     }),
+    payload.updateGlobal({
+      slug: 'newsletter-form',
+      context: { disableRevalidate: true },
+      data: defaultNewsletterFormData as never,
+    }),
   ])
 
   payload.logger.info('Preloaded global CMS settings.')