Update location rules templates to new target

[hamishmorgan]

Part of the ongoing project to rationalise the function API

gsd#44156 | doc | style guide | slack

This PR updates the Order Routing Location Rules templates

Specifically:

• Pulled the latest schema. (shopify app function schema in an location rules extension with the function_renaming_breaking_changes_api flag enabled, and the order_routing_extensibility_partner partner flag enabled.) The diff is a bit scary because it hasn't been updated in ages.
• Updated the sample code, replacing the target handle and result types.
• Bumped the version to 2025-07 where appropriate

[tjoyal]

What I see here looks good.

Approving, but either here or as a followup PR we'll need to update the export name and GraphQL schema file name as per #623