1. correct the modal usage on "admin email list" page (then
`web_src/js/features/admin/emails.ts` is removed)
2. use `addDelegatedEventListener` instead of `jQuery().on`
3. more jQuery related changes and remove jQuery from
`web_src/js/features/common-button.ts`
4. improve `confirmModal` to make it support header, and remove
incorrect double-escaping
5. fix more typescript related types
6. fine tune devtest pages and add more tests
make preventDuplicates default to true, users get a clear UI feedback
and know that "a new message appears".
Fixes: https://github.com/go-gitea/gitea/issues/26651
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Co-authored-by: silverwind <me@silverwind.io>
