feat: add script to update from main

[igobranco]

Add a script to make it more easy to update the current translations with the fixes and new translations from the upstream main.

This PR adds a Python script that updates the current translations from the upstream main translations.
So from a previous release we can make it more easy just receive the latest patched (fixed) and/or new translations.

Use cases:

1. Some translations is 'fixed' on transifex and with this script we can update the open release branch with the latest translations.
2. Instead of having to fix both release and head translations to operator can just receive the new translations.

---

Copied from the script comment:

Update release branch translations with fixes and new strings from the main branch.

This script synchronizes translation files between a release branch and an upstream branch
(typically 'main'). It supports both JSON and PO (gettext) translation files.

Key features:
- Fetches upstream translations from a git branch (no local clone needed)
- Merges translations preferring upstream fixes over local versions
- Adds new translation strings from upstream that don't exist locally
- Preserves PO file formatting using msgcat with --no-wrap
- Supports filtering by language code and file type

For JSON files:
- Parses both local and upstream JSON files
- Adds new translation keys from upstream
- Preserves existing local translations for unchanged keys
- Sorts keys alphabetically for consistency

For PO files:
- Uses msgcat with --use-first to prefer upstream msgstr values (fixes)
- Uses --no-wrap to preserve original line formatting
- Uses --sort-output for consistent entry ordering
- Maintains proper gettext format and metadata

Usage:
    python update_from_main.py [OPTIONS]

Examples:
    # Update all languages and file types from main branch
    python update_from_main.py --branch main
    
    # Update only Portuguese translations
    python update_from_main.py --language pt_PT
    
    # Update only PO files for multiple languages
    python update_from_main.py --language pt_PT --language es_419 --file-type po
    
    # Dry run to preview changes
    python update_from_main.py --dry-run
    
    # Update from a different upstream repository
    python update_from_main.py --branch nau/redwood.master --upstream-repo https://github.com/openedx/openedx-translations.git

[openedx-webhooks]

Thanks for the pull request, @igobranco!

This repository is currently maintained by @openedx/committers-translations.

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