feat(plugin-search): add full translation support

[MrFlathill]

What?

This change integrates the new @payloadcms/translations package, enabling full internationalization for the search plugin's administrative interface.

Why

To enhance the plugin's usability and accessibility for a global audience by providing its administrative interface in multiple languages. This change allows developers to easily translate all user-facing strings within the plugin-search functionality, ensuring a consistent and localized experience.

How?

• Translation Integration: The @payloadcms/translations package is now a dependency of plugin-search.
• Translatable UI Elements: All collection labels, field labels (label), and descriptions within the Search collection are updated to use translation functions (({ t }) => t('plugin-search:key')) instead of hardcoded strings.
• Plugin Translations Registered: The plugin's default translations (English, German, Italian) are automatically merged into the Payload config's i18n settings.
• Translation Export: The plugin's translations are exported as searchTranslations for external use.
• UI Field Component Update: The LinkToDoc UI field is updated to be a UIFieldServerComponent, allowing its label to be translated server-side and passed to the client component.
• Test Suite Enhancements: The plugin-search test environment now includes seed data for pages and posts collections, which is essential for thoroughly testing the plugin's functionality, including its newly translatable elements.
• Removing unused dependencies

Testing

• pnpm build:plugin-search
• pnpm --filter @payloadcms/plugin-search build
• pnpm test:int ./test/plugin-search/int.spec.ts
• Manually tested the plugin with pnpm dev plugin-search , with German and Italian admin i18n and verified plugin translation keys can be resolved and overridden.