[Customer] Deprecate region_id from customer address region

[paliarush]

Region ID is excessive on storefront and region code should suffice for all scenarios.

Acceptance criteria:

• deprecate id in Region
• deprecate region_id in CustomerAddressRegionInput, CustomerAddressRegion, CustomerAddress
• Input types do not support @deprecated directive, so comments should be used instead
• Document replacement for these fields as region_code or code depending on the context