Add search bar to `ListPersonSaved`

### Requirements - [x] This is a feature request and not a bug report. Otherwise, please create a new [bug report](https://github.com/LemmyNet/lemmy-ui/issues/new?assignees=&labels=bug%2Ctriage&projects=&template=BUG_REPORT.yml) instead. - [x] Please [check](https://github.com/LemmyNet/lemmy-ui/issues) to see if this request (or a similar one) already exists. - [x] It's a single feature. Please don't request multiple features in one issue. ### Describe the feature you'd like Add the ability to search within your saved content. Entails adding a search field to the saved tab. Context: https://github.com/LemmyNet/lemmy/issues/4547