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/resources/app/commerce-modules/cart/promotions/page.mdx

@@ -18,13 +18,13 @@ The `LineItemAdjustment` data model represents changes on a line item, and the `
 
 ![A diagram showcasing the relations between other data models and adjustment line models](https://res.cloudinary.com/dza7lstvk/image/upload/v1711534248/Medusa%20Resources/cart-adjustments_k4sttb.jpg)
 
-The `amount` field of the adjustment line indicates the amount to be discounted from the original amount. Also, the ID of the applied promotion is stored in the `promotion_id` field of the adjustment line.
+The `amount` property of the adjustment line indicates the amount to be discounted from the original amount. Also, the ID of the applied promotion is stored in the `promotion_id` property of the adjustment line.
 
 ---
 
 ## Discountable Option
 
-The `LineItem` data model has an `is_discountable` field that indicates whether promotions can be applied to the line item. It’s enabled by default.
+The `LineItem` data model has an `is_discountable` property that indicates whether promotions can be applied to the line item. It’s enabled by default.
 
 When disabled, a promotion can’t be applied to a line item. In the context of the Promotion Module, the promotion isn’t applied to the line item even if it matches its rules.
 
@@ -50,7 +50,7 @@ import {
 } from "@medusajs/types"
 
 // retrieve the cart
-const cart = await cartModuleService.retrieve("cart_123", {
+const cart = await cartModuleService.retrieveCart("cart_123", {
   relations: [
     "items.adjustments",
     "shipping_methods.adjustments",