fix(live-preview-vue): update build config to compile as esm

[danielwaltz]

The distributed files for @payloadcms/live-preview-vue are compiled to commonjs instead of ESM, which causes issues in ESM based projects like when using Nuxt.

This PR fixes this issue by updating the built config to be es6, matching what most other packages are using.

Related to #12806

[github-actions[bot]]

Pull Request titles must follow the Conventional Commits specification and have valid scopes.

Unknown scope "live-preview-vue" found in pull request title "fix(live-preview-vue): update build config to compile as esm". Scope must match one of: cpa, db-*, db-d1-sqlite, db-mongodb, db-postgres, db-vercel-postgres, db-sqlite, db-d1-sqlite, drizzle, email-*, email-nodemailer, email-resend, eslint, graphql, live-preview, live-preview-react, next, payload-cloud, plugin-cloud, plugin-cloud-storage, plugin-ecommerce, plugin-form-builder, plugin-import-export, plugin-multi-tenant, plugin-nested-docs, plugin-redirects, plugin-search, plugin-sentry, plugin-seo, plugin-stripe, richtext-*, richtext-lexical, richtext-slate, sdk, storage-*, storage-azure, storage-gcs, storage-r2, storage-uploadthing, storage-vercel-blob, storage-s3, translations, ui, templates, examples(/(\w|-)+)?, deps.

feat(ui): add Button component
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