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`

package.json

@@ -76,6 +76,7 @@
     "test:integration:plugins": "turbo run test --no-daemon --filter=integration-tests-plugins",
     "test:integration:repositories": "turbo run test --no-daemon --filter=integration-tests-repositories",
     "openapi:generate": "yarn ./packages/oas/oas-github-ci run ci",
+    "medusa-oas": "yarn ./packages/oas/medusa-oas-cli run medusa-oas",
     "generate:services": "typedoc --options typedoc.services.js",
     "generate:js-client": "typedoc --options typedoc.js-client.js",
     "generate:entities": "typedoc --options typedoc.entities.js",