[mod] reduce memory footprint by not calling babel.Locale.parse at runtime

babel.Locale.parse loads more than 60MB in RAM.  The only purpose is to get:

    LOCALE_NAMES   - searx.data.LOCALES["LOCALE_NAMES"]
    RTL_LOCALES    - searx.data.LOCALES["RTL_LOCALES"]

This commit calls babel.Locale.parse when the translations are update from
weblate and stored in::

    searx/data/locales.json

This file can be build by::

    ./manage data.locales

By store these variables in searx.data when the translations are updated we save
round about 65MB (usually 4 worker = 260MB of RAM saved.

Suggested-by: https://github.com/searxng/searxng/discussions/2633#discussioncomment-8490494
Co-authored-by: Markus Heiser <markus.heiser@darmarit.de>

utils/lib_sxng_data.sh

@@ -7,6 +7,7 @@ data.:
   all       : update searx/sxng_locales.py and searx/data/*
   traits    : update searx/data/engine_traits.json & searx/sxng_locales.py
   useragents: update searx/data/useragents.json with the most recent versions of Firefox
+  locales   : update searx/data/locales.json from babel
 EOF
 }
 
@@ -16,6 +17,7 @@ data.all() {
         pyenv.activate
         data.traits
         data.useragents
+	data.locales
 
         build_msg DATA "update searx/data/osm_keys_tags.json"
         pyenv.cmd python searxng_extra/update/update_osm_keys_tags.py
@@ -49,6 +51,15 @@ data.useragents() {
     dump_return $?
 }
 
+data.locales() {
+    (   set -e
+        pyenv.activate
+        build_msg DATA "update searx/data/locales.json"
+        python searxng_extra/update/update_locales.py
+    )
+    dump_return $?
+}
+
 docs.prebuild() {
     build_msg DOCS "build ${DOCS_BUILD}/includes"
     (