Make product options and option groups channel-aware

[asonnleitner]

Is your feature request related to a problem? Please describe.
In the current Vendure implementation, product options and option groups are not channel-aware. Our production data analysis shows severe data duplication:

• From 1.3M product options, 1.17M (88.7%) are duplicates
• From 263K option groups, 263.9K (99.9%) are duplicates
• From 10.2M option translations, 10.1M (98.3%) are duplicates
• From 2.6M option group translations, 2.63M (99.9%) are duplicates

This leads to:

1. Massive database bloat
2. Performance degradation due to duplicate data
3. Maintenance overhead when updating options across channels
4. Consistency issues when managing the same options in different channels

Describe the solution you'd like
Make ProductOptionGroup, ProductOptionGroupTranslation, ProductOption, and ProductOptionTranslation entities channel-aware by:

1. Adding Many-to-Many relationships with Channel entity
2. Updating GraphQL schema to support channel operations
3. Providing migration path for existing data
4. Updating admin UI to support channel-specific option management

This would allow users to manage options per channel without creating duplicates.

Additional context
SQL query used for analysis:

SELECT
    (SELECT COUNT(*) FROM product_option) AS product_option,
    (SELECT COUNT(*) FROM product_option_translation) AS product_option_translation,
    (SELECT COUNT(*) FROM product_option_group) AS product_option_group,
    (SELECT COUNT(*) FROM product_option_group_translation) AS product_option_group_translation,
    (SELECT COUNT(*) - COUNT(DISTINCT code) FROM product_option) AS duplicate_codes_in_product_option,
    (SELECT COUNT(*) - COUNT(DISTINCT code) FROM product_option_group) AS duplicate_codes_in_product_option_group,
    (SELECT COUNT(*) - COUNT(DISTINCT name) FROM product_option_translation) AS duplicate_names_in_product_option_translation,
    (SELECT COUNT(*) - COUNT(DISTINCT name) FROM product_option_group_translation) AS duplicate_names_in_product_option_group_translation;

Results showing the scale of duplication:

{
    "product_option": 1325768,
    "product_option_translation": 10268769,
    "product_option_group": 263903,
    "product_option_group_translation": 2638193,
    "duplicate_codes_in_product_option": 1176201,
    "duplicate_codes_in_product_option_group": 263901,
    "duplicate_names_in_product_option_translation": 10099216,
    "duplicate_names_in_product_option_group_translation": 2638161
}