[mod] manage - implement babel commands, drop update_translations.sh

In ./manage implement babel.*:

-  extract   : extract messages from source files and generate POT file
-  update    : update existing message catalogs from POT file
-  compile   : compile translation catalogs into binary MO files

Replace searx_extra/update/update_translations.sh by command:

- ci.babel.update

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Makefile

@@ -77,7 +77,7 @@ test.shell:
 # wrap ./manage script
 
 MANAGE += buildenv
-MANAGE += babel.compile
+MANAGE += ci.babel.update babel.extract babel.update babel.compile
 MANAGE += data.all data.languages data.useragents data.osm_keys_tags
 MANAGE += docs.html docs.live docs.gh-pages docs.prebuild docs.clean
 MANAGE += docker.build docker.push docker.buildx