fix: translated "Search" in search box (#521)
* fix: translated "Search" in search box
Implemented i18n for term "Search" in search box. Added translation
(mostly "Search") in i18n/*.toml files.
* Fix search translation not applied to posts + update translations
Co-authored-by: stueja <jan@jbook.js73.de>
Co-authored-by: Emruz Hossain <hossainemruz@gmail.com>