feat: extract sync_and_translate_language into new ol_openedx_ai_static_translations plugin

[Copilot]

Moves the sync_and_translate_language management command and all supporting code out of ol_openedx_course_translations into a standalone plugin within open-edx-plugins (not ol-django).

New plugin: ol_openedx_ai_static_translations

• Follows existing plugin conventions (pyproject.toml, setup.cfg, apps.py, settings, etc.)
• Flat module layout — no utils/ package. command_utils.py + translation_sync.py merged into a single utils.py; constants.py lives at the package root
• CMS-only entry point with its own settings for sync-specific config (TRANSLATIONS_GITHUB_TOKEN, TRANSLATIONS_REPO_URL, TRANSLATIONS_REPO_PATH)
• Glossary files included in the new plugin
• Dependencies: GitPython, litellm, polib, requests

Changes to ol_openedx_course_translations

• Removed sync-specific settings from settings/common.py (now owned by the new plugin)
• Glossary files retained (kept in both plugins)
• No functional changes to translate_course or any other existing code

Removed

• ol_django_plugin/ directory from prior iteration

Import structure

# management command imports
import ol_openedx_ai_static_translations.utils as utils_module
from ol_openedx_ai_static_translations.constants import PLURAL_FORMS, ...
from ol_openedx_ai_static_translations.utils import sync_all_translations, ...

Glossary path resolution updated from .parent.parent → .parent to reflect the flat layout (utils.py at package root instead of utils/translation_sync.py).

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[asadali145]

Closing in favor of #769