Adds a print statement to `tools/i18n/update-for-legacy-translations`
to help with debugging to know what locale was being checked if an
error is raised.
Adds tools/i18n/create-legacy-stream-translations to create a
`legacy_stream_translations.json` file for every non-English
language locale that will serve as the legacy translations for
the stream to channel rename.
Adds tools/i18n/update-for-legacy-translations to manage adding
the legacy translations for any stream/channel strings that we'd
like to maintain existing translations for, which are defined in
LEGACY_STRINGS_MAP.
Shubham Padia
Anders Kaseorg
Lauryn Menard