docs: updates to use DML and other changes (#7834)

- Change existing data model guides and add new ones for DML
- Change module's docs around service factory + remove guides that are now necessary
- Hide/remove all mentions of module relationships, or label them as coming soon.
- Change all data model creation snippets to use DML
- use `property` instead of `field` when referring to a data model's properties.
- Fix all snippets in commerce module guides to use new method suffix (no more main model methods)
- Rework recipes, removing/hiding a lot of sections as a lot of recipes are incomplete with the current state of DML.


### Other changes

- Highlight fixes in some guides
- Remove feature flags guide
- Fix code block styles when there are no line numbers.

### Upcoming changes in other PRs

- Re-generate commerce module references (for the updates in the method names)
- Ensure that the data model references are generated correctly for models using DML.
- (probably at a very later point) revisit recipes

www/apps/book/app/basics/medusa-container/page.mdx

@@ -15,7 +15,7 @@ You use the Medusa container to resolve resources, such as services.
 For example, in a custom API route you can resolve any service registered in the Medusa application using the `scope.resolve` method of the `MedusaRequest` parameter:
 
 export const highlights = [
-  ["13", "resolve", "Resolve the `IProductModuleService`"],
+  ["13", "resolve", "Resolve the Product Module's main service."],
   ["13", "ModuleRegistrationName.PRODUCT", "The resource registration name imported from `@medusajs/modules-sdk`."]
 ]
 
@@ -41,5 +41,3 @@ export const GET = async (
   })
 }
 ```
-
-You resolve the `IProductModuleService` and uses it to return the full count of products in the Medusa application.