Address
https://github.com/go-gitea/gitea/pull/25163#issuecomment-1599207916
Remove the unused "icon-button".
And fix the layout:
Without the dropdown icon:
```
{{svg "gitea-whitespace"}}
```

With the dropdown icon:
```
{{svg "gitea-whitespace" 16 "gt-mr-3"}}
{{svg "octicon-triangle-down" 14 "dropdown icon"}}
```

This refactors the `shared/datetime/short|long|full` templates into a
template helper function, which allows us to render absolute date times
within translatable phrases.
- Follows #23988
- The first attempt was in #24055
- This should help #22664
Changes:
1. Added the `DateTime` template helper that replaces the
`shared/datetime/short|long|full` templates
2. Used find-and-replace with varying regexes to replace the templates
from step 1 (for example, `\{\{template "shared/datetime/(\S+) \(dict
"Datetime" ([^"]+) "Fallback" ([^\)]+\)?) ?\)?\}\}` -> `{{DateTime "$1
$2 $3}}`)
3. Used the new `DateTime` helper in the issue due date timestamp
rendering
# Before

# After

---------
Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>