Add option to select jp-tok region

[vburckhardt]

Description

• Ensure that all services in the stack can deploy in that region.
• If this works - add support for Japan jp-tok region at the stack level https://github.com/terraform-ibm-modules/stack-retrieval-augmented-generation/blob/df61899f03da8e2f98ed26948eb93a92a8a375b7/ibm_catalog.json#L219

[Soaib024]

@vburckhardt As of now, Watsonx SaaS DA is only supported in us-south and eu-de. so should I close this issue?

https://github.com/terraform-ibm-modules/terraform-ibm-watsonx-saas-da/blob/d243f4db0960e337c45e6c940659bdcdf2256748/variables.tf#L14

[vburckhardt]

@Soaib024 - I think watson services can be deployed in jp however, and if so, the approach here would be to update the watsonx saas da.

[Soaib024]

Occupied with some other works, so unassigning for now