[FEATURE] translate should update target if source record is changed

[mcm1957]

a) Currently npm run translate writes translated text records into the target files only if the corresponding record does not exist there.

npm run translate should keep a record of the source file (i18n/en/translate,json) and hence detect if a text has been changed. In this case the target records should be replaced with the new translations too. Note: npm run traslate MUST NOT write the full target file if no change in source json is detected as this would override manual corrections.

b) at least optionally npm translate should remove outdated record from the target files. Outdated records should be defined as records no longer exist in source file.

[mcm1957]

Please consider WEBLATE integration when adapting anything in this area. Maybe weblate should leave some marker to contraol behavior of trabslate script - or vice versa.