feat(core): adjust filter area style (#12534)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **New Features**
  - Added support for displaying the "Add Filter" action as either an icon button or a labeled button, depending on the filter state.
  - Introduced a localized label for the "Add Filter" button.

- **Style**
  - Improved filter area layout and styling for better visual consistency.
  - Adjusted padding and added styles to hide empty filter values.

- **Bug Fixes**
  - Updated test identifiers for filter value elements to improve test reliability.

- **Documentation**
  - Added a new English localization string for the "Add Filter" button.

- **Chores**
  - Updated translation completeness percentages for various locales.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/i18n/src/resources/en.json

@@ -517,6 +517,7 @@
   "com.affine.favoritePageOperation.add": "Add to favourites",
   "com.affine.favoritePageOperation.remove": "Remove from favourites",
   "com.affine.filter": "Filter",
+  "com.affine.filter.add-filter": "Add Filter Rule",
   "com.affine.filter.after": "after",
   "com.affine.filter.before": "before",
   "com.affine.filter.contains all": "contains all",