feat(codegen): x-expanded-relations (#3442)

## What

Alter generated types base on `x-expanded-relations` OAS extension declared on schemaObjects.

## Why

Often, API endpoints will automatically expand a model relations by default. They can also decorate a model with calculated totals. In order to more accurately represent the API, we wish to alter the generated types based on the expanded relations information.

## How

- Follow the relation declaration signature as the backend controllers and the `expand` query param, i.e.: `items.variant.product`.
- Introduce a custom `x-expended-relations` OAS extension.
- Allow for organizing declared relations to help their maintenance.
- Use traversal algorithms in codegen to support deeply nested relationships.
- Use [type-fest](https://www.npmjs.com/package/type-fest)'s `Merge` and `SetRequired` to efficiently alter the types while enabling great intellisense for IDEs.

Extra scope: 
* Added convenience yarn script to interact with the `medisa-oas` CLI within the monorepo. 

## Test

Include in the PR are two implementations of the x-expanded-relations on OAS schema, a simple and a complex one.

### Step 1
* Run `yarn install`
* Run `yarn build`
* Run `yarn medusa-oas oas --type combined --out-dir ~/tmp/oas`
* Run `yarn medusa-oas client --type combined --component types --src-file ~/tmp/oas/combined.osa.json --out-dir ~/tmp/types`
* Open `~/tmp/types/models/StoreRegionsRes`
* Expect relations to be declared as required

### Step 2
* Open `~/tmp/types/models/StoreCartsRes`
* Expect relations to be declared as required
* Expect nested relations to have relations as required.

### Step 3 (optional)
* Open `~/tmp/types` in an intellisense capable IDE
* Within the `index.ts` file, attempt to declare a `const storeRegionRes: StoreRegionRes = {}`
* Expect IDE to highlight that `countries` is a required field of `StoreRegionRes`

packages/medusa/src/api/routes/store/carts/index.ts

@@ -154,6 +154,52 @@ export const defaultStoreCartRelations = [
 /**
  * @schema StoreCartsRes
  * type: object
+ * x-expanded-relations:
+ *   field: cart
+ *   relations:
+ *     - billing_address
+ *     - discounts
+ *     - discounts.rule
+ *     - gift_cards
+ *     - items
+ *     - items.adjustments
+ *     - items.variant
+ *     - payment
+ *     - payment_sessions
+ *     - region
+ *     - region.countries
+ *     - region.payment_providers
+ *     - shipping_address
+ *     - shipping_methods
+ *     - shipping_methods.shipping_option
+ *   implicit:
+ *     - items.tax_lines
+ *     - items.variant.product
+ *     - region.fulfillment_providers
+ *     - region.payment_providers
+ *     - region.tax_rates
+ *     - shipping_methods.shipping_option
+ *     - shipping_methods.tax_lines
+ *   totals:
+ *     - discount_total
+ *     - gift_card_tax_total
+ *     - gift_card_total
+ *     - item_tax_total
+ *     - refundable_amount
+ *     - refunded_total
+ *     - shipping_tax_total
+ *     - shipping_total
+ *     - subtotal
+ *     - tax_total
+ *     - total
+ *     - items.discount_total
+ *     - items.gift_card_total
+ *     - items.original_tax_total
+ *     - items.original_total
+ *     - items.refundable
+ *     - items.subtotal
+ *     - items.tax_total
+ *     - items.total
  * required:
  *   - cart
  * properties:

packages/medusa/src/api/routes/store/regions/index.ts

@@ -16,6 +16,12 @@ export default (app) => {
 /**
  * @schema StoreRegionsListRes
  * type: object
+ * x-expanded-relations:
+ *   field: regions
+ *   relations:
+ *     - countries
+ *     - payment_providers
+ *     - fulfillment_providers
  * required:
  *   - regions
  * properties:
@@ -31,6 +37,12 @@ export type StoreRegionsListRes = {
 /**
  * @schema StoreRegionsRes
  * type: object
+ * x-expanded-relations:
+ *   field: region
+ *   relations:
+ *     - countries
+ *     - payment_providers
+ *     - fulfillment_providers
  * required:
  *   - region
  * properties: